ALBERT

Description: Gas data of the Los Azufres geothermal field were analyzed using a method based on equilibrium of the Fischer- Tropsch (FT) reaction: CH4 + 2H2O = 4H2 +CO2 and on the combined pyrite-hematite-magnetite (HSH2) reactions: 5/4 H2 +3/2 FeS2 +3/4 Fe2O3 + 7/4 H2O = 3 H2S +Fe3O4 in order to estimate reservoir temperature and excess steam. The solution of equilibrium equations produces a grid (FT-HSH2). This method is suitable for reservoirs with relatively high H2S but low H2 and NH3 concentrations in the fluid as is the case of the Los Azufres well discharges. Reservoir temperature and reservoir excess steam values were estimated for initial and present conditions in representative wells of the field to study the evolution of fluids, because of exploitation and waste fluids reinjection. This method was very useful in estimating reservoir temperatures in vapor wells, while in two-phase wells it was found that as the well produces a smaller fraction of water, the reservoir temperature estimation agrees qualitatively with results from cationic or silica geothermometers. For liquid-dominated wells the reservoir temperature estimations agree with temperatures obtained from the well simulator WELFLO. This indicates that FT-HSH2 results provide the temperature of the fluid entering the well where the last equilibrium occurs. Results show a decrease in reservoir temperatures in the southern zone of the field where intensive reinjection takes place. With exploitation, it was also noted that the deep liquid phase in the reservoir is changing to two-phase increasing the reservoir steam fraction and the non-condensable gases in well discharges.

Description: Published

Description: JCR Journal

Description: open

Description: Geochemical investigations have shown that there is a considerable inflow of gas into both crater lakes of Monticchio, Southern Italy. These lakes are located in two maars that formed 140,000 years ago during Mt. Vulture volcano’s last eruptive activity. Isotopic analyses suggest that CO2 and helium are of magmatic origin; the latter displays 3He/4He isotope ratios similar to those measured in olivines of the maar ejecta. In spite of the fact that the amount of dissolved gases in the water is less than that found in Lake Nyos (Cameroon), both the results obtained and the historical reports studied indicate that these crater lakes could be highly hazardous sites, even if they are located in a region currently considered inactive. This could be of special significance in very popular tourist areas such as the Monticchio lakes, which are visited by about 30,000 people throughout the summer, for the most part on Sundays.

Description: In press

Description: 83-87

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: open

Description: Between April 10th and May 22th 2006, a small seismic swarm of 5 volcano-tectonic events occurred on the volcanic island of Stromboli (Southern Italy). Two of these, having M 〉 3 and an intensity of about V-VI MCS, were clearly felt causing concern in the population. They were recorded during a period of increased explosive activity and were followed by two major explosions at the summit craters on May 22th, few hours after the last earthquake and on 16th June. The location of such events has been performed using a probabilistic approach based on the Equal Differential Time tecnique. Using this tecnique, we were able to locate all the events, showing how they cluster below the volcanic edifice at a depth of about 5÷6 km. From observed P wave polarities we determined the focal mechanisms of the 4 major events. Using earthquake scaling nlaws, we calculated the fault area and the average slip for the two major events. Finally, assuming an homogeneous half-space model we computed the isotropic stress changes below the volcano edifice. The negative stress variation over the central axis of the volcano suggests that the earthquakes were triggered by a pressurization of the magmatic system.

Description: Published

Description: open

Description: The CO2 degassing process from a large area on the Tyrrhenian side of central Italy, probably related to the input into the upper crust of mantle fluids, was investigated in detail through the geochemical study of gas emissions and groundwater. Mass-balance calculations and carbon isotopes show that over 50% of the inorganic carbon in regional groundwater is derived from a deep source highlighting gas−liquid separation processes at depth. The deep carbonate−evaporite regional aquifer acts as the main CO2 reservoir and when total pressure of the reservoir fluid exceeds hydrostatic pressure, a free gas phase separates from the parent liquid and escapes toward the surface generating gas emissions which characterise the study area. The distribution of the CO2 flux anomalies and the location of high PCO2 springs and gas emissions suggest that the storage and the expulsion of the CO2 toward the atmosphere are controlled by the geological and structural setting of the shallow crust. The average CO2 flux and the total amount of CO2 discharged by the study area were computed using surface heat flow, enthalpy and CO2 molality of the liquid phase circulating in the deep carbonate−evaporite aquifer. The results show that the CO2 flux varies from 1×104 mol y−1 km−2 to 5×107 mol y−1 km−2, with an average value of 4.8×106 mol y−1 km−2, about five times higher than the value of 1×106 mol y−1 derived by Kerrick et al. [Kerrick, D.M., McKibben, M.A., Seward, T.M., Caldeira, K., 1995. Convective hydrothermal CO2 emission from high heat flow regions. Chem. Geol. 121, 285–293] as baseline for terrestrial CO2 emissions. The total CO2 discharged from the study area is 0.9×1011 mol y−1, confirming that Earth degassing from Tyrrhenian central Italy is a globally relevant carbon source

Description: Published

Description: 89–102

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: 4.5. Degassamento naturale

Description: JCR Journal

Description: reserved

Description: The GSHAP CAUCAS test area was established under the INTAS Ct.94-1644 (Test Area for sismic Hazard Assessment in the Caucasus) and NATO ARW Ct.95-1521 (Historical and Prehistorical Earthquakes in the Caucasus), with the initial support of IASPEI, UNESCO and ILP. The high tectonic interest and seismicity rate of the whole area, the availability of abundant multi-disciplinary data and the long established tradition in hazard assessment provide a unique opportunity to test different methodologies in a common test area and attempt to establish some consensus in the scientific community. Starting from the same input data (historical and instrumental seismic catalogue, lineament and homogeneous seismic source models) six independent approaches to seismic hazard assessment have been used, ranging from pure historical deterministic to seismotectonic probabilistic and areal assessment methodologies. The results are here compared.

Description: JCR Journal

Description: open

Description: Earthquake Early Warning Systems (EEWS), based on real-time prediction of ground motion or structural response measures, may play a role in reducing vulnerability and/or exposition of buildings and lifelines. In fact, recently seismologists developed efficient methods for rapid estimation of event features by means of limited information of the P-waves. Then, when an event is occurring, probabilistic distributions of magnitude and source-to-site distance are available and the prediction of the ground motion at the site, conditioned to the seismic network measures, may be performed in analogy with the Probabilistic Seismic Hazard Analysis (PSHA). Consequently the structural performance may be obtained by the Probabilistic Seismic Demand Analysis (PSDA), and used for real-time risk management purposes. However, such prediction is performed in very uncertain conditions which have to be taken into proper account to limit false and missed alarms. In the present study, real-time risk analysis for early warning purposes is discussed. The magnitude estimation is performed via the Bayesian approach, while the earthquake localization is based on the Voronoi cells. To test the procedure it was applied, by simulation, to the EEWS under development in the Campanian region (southern Italy). The results lead to the conclusion that the PSHA, conditioned to the EEWS, correctly predicts the hazard at the site and that the false/missed alarm probabilities may be controlled by set up of an appropriate decisional rule and alarm threshold.

Description: Published

Description: 867–885

Description: open

Description: The plain of Gubbio is located in a northwest-southeast oriented, 4-km wide, 20-km long intermountain basin in the northern Apennines, central Italy. The moderate-magnitude earthquakes of the 1997 Umbria-Marche seismic sequence, occurred 40 km southeast of Gubbio, generated displacements as large as 6 cm within the basin. The large amplitude phase, not observed outside of the basin, was followed by low-frequency wave trains lasting up to 1 minute. In order to investigate the mechanism of possible local amplification effects, different kind of geophysical and geological investigation of the basin started within the framework of the Italian DPC-INGV projects. In particular, the GFZ and the INGV deployed two linear seismic arrays. The first one was composed of ten seismological stations with 1-s receivers. It operated from June until December 2005. The array was oriented north-south, approximately: all the stations but two were installed on the sedimentary deposits. The remaining two stations (the northernmost and the southernmost) were installed on rock outcrops at the edges of the basin. The second array, composed by 10 stations with 5-s receivers, was deployed along the main axis of the basin, and is recording since November 2005. For 45 days, the two arrays worked simultaneously. A selected dataset of 250 earthquakes has been analyzed. H/V spectral ratio results show that systematic low-frequency (0.3-0.4 Hz) amplification affects the stations in the middle of the basin. The resonance frequency peaks are consistent with the thickness and the average S-wave velocity of soft sediments derived from microtremor measurements in the basin. The conventional spectral ratio results show a more complex broad-band (0.3-10 Hz) amplification. The analysis of selected records by means of a sonogram approach highlights the arrival of strong late phases increasing the signal duration at the stations located in the middle of the basin.

Description: Unpublished

Description: Geneva, Switzerland

Description: open

Description: Five Andean countries (Bolivia, Peru, Ecuador, Colombia, Venezuela) and four European countries (Italy, Spain, Holland, Germany) cooperated in the PILOTO program ("Test area for earthquake monitoring and seismic hazard assessment"), launched under GSHAP and sponsored by the European Union (Ct.94-0103) to produce a unified SHA for the Andean region. Activities included the integration of national earthquake catalogues and source zonings in common regional databases and joint technical workshops for the assessment of the regional hazard, expressed in terms of expected peak ground acceleration with 10% exceedance probability in 50 years.

Description: JCR Journal

Description: open

Description: This article presents the results of a detailed study of the effects of the 1883 earthquake, which occurred at the island of Ischia (Gulf of Naples) and produced the total destruction of buildings in the epicentral area (Casamicciola town). Despite the moderate magnitude, this event was characterised by very high intensities (Imax = XI degree MCS) mainly due to the shallow depth of the source. The study of the earthquake shows that the intensities, which decreased rapidly with distance, were affected by source directivity, according to the causative fault geometry and tectonic structures, while local amplification of damage was observed where soft soils outcrop. The attenuation of seismic intensity with distance was evaluated using the well-known relation of intensity versus epicentral distance (Blake’s method). The diverse gradients of attenuation, observed in different directions, were ascribed to the various geological features of the shallow crust of the island. In order to evaluate the role of geology in the damage level, we computed different attenuation models for stiff and soft soils outcropping on the island. A systematic local amplification of about 1 MCS degree associated to the presence of reworked tuffs was obtained. This study also shows the influence of geological conditions on the evaluation of macroseismic data and supplies useful elements to derive a predictive map of potential site effects.

Description: Published

Description: id 231

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: reserved

Description: Results of probabilistic seismic hazard assessment (PSHA), in terms of macroseismic intensity applied to the Mt. Etna region, are presented. PSHA has been performed using a numerical procedure based on the extensive use of local macroseismic information, as an alternative to the usual Cornell-McGuire methods. The large amount of intensity data available for this area - coming from the Italian intensity database DBMI04 for the regional earthquakes, and from the Etna catalogue for the ‘local’ events - has provided fairly exhaustive seismic site histories (i.e. the data set of macroseismic observations available for a given locality) to estimate the seismic hazard for 402 localities on the volcano. In order to improve the completeness of the site catalogue when historical information is missing, observed intensity data have been integrated with values calculated from epicentral information obtained by using an attenuation law specific for the Etna region. Using a probability distribution considering the completeness of the input database and the uncertainty of intensity data, the hazard in terms of maximum intensity (Iexp) characterised by a 10% probability of exceedance in an exposure time of 50 years, has been computed. The highest values ( Iexp = IX or X) are found in the south-eastern flank of Mt. Etna while the rest of the volcano is exposed to a lower hazard (Iexp = VIII). Despite the low energy (M≤4.8) compared with that of the large regional earthquakes affecting the area (6.6≤M≤7.4), the local events strongly influence the pattern of the hazard in the eastern sector of Mt. Etna, representing a significant, and sole, source of hazard when a shorter exposure time (e.g. 30 years) is considered.

Description: Published

Description: 77-91

Description: N/A or not JCR

Description: reserved

Description: We present the first helium isotope data for thermal waters and gas emissions on the islands of Terceira, Graciosa, Faial, Pico and Flores, as well as new data for Sao Miguel. The results allow us to track current mantle degassing associated with the Azores hot spot, to delineate its spatial distribution and to discuss its possible origin. As a general rule, we find that free gases tend to display somewhat higher 3He/4He ratio than groundwaters.We argue that this difference is likely due to radiogenic helium inputs to aquifers duringwater– rock interactions and, therefore, that gas phases are the fluid carriers with the most representative of mantle source signature. The measured 3He/4He ratios (normalized to the air ratio, Ra) range from lower-than-MORB values (5.23–6.07 Ra) on central Sao Miguel, to MORB values on Faial (8.53 Ra) and Flores (8.04 Ra) – located on either side of the Mid-Atlantic Ridge – and to plume-type values on Graciosa (11.2 Ra) and Terceira (13.5 Ra) where free gases also display ten times higher-than-MORB CO2/3He ratios (1.8–2.6×1010). Such a wide He isotopic range and its spatial distribution corroborate with available data for volcanic rocks, indicating that plume's head presently underlies the central part of the archipelago. The plume-type 3He/4He ratios on Terceira and Graciosa agree with geochemical and seismic evidence of a deep-rooted mantle plume feeding the Azores hot spot. Our finding that high 3He/4He ratios correspond to low 3He concentrations and high (arctype) CO2/3He values exclude a simple plume supply of 3He-rich primitive mantle. Instead, the simultaneity of both elevated CO2/3He and 3He/4He ratios is best explained by a 3He-rich contribution from the lower mantle diluted in a CO2-rich feeding plume that contains a recycled altered oceanic plate component. The alternative possibility of an enhanced time-integrated 3He/(U+Th) ratio in the Azores plume due to a greater compatibility of helium relative to U and Th during melting events is difficult to reconcile with the enriched pattern of volcanic rocks from the central islands. In any case, the Azores plume should derive from a mantle reservoir that could escape convective homogenization for a very long period of time, in agreement with subchondritic osmium isotopic ratios in volcanic rocks from the central islands of the archipelago.

Description: Published

Description: 70−80

Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Description: JCR Journal

Description: reserved

Description: Probabilistic seismic hazard analysis is currently the soundest basis for the rational evaluation of ground-motion hazard for site-specific engineering design and assessment purposes. An increasing number of building codes worldwide acknowledge the uniform hazard spectra as the reference to determine design actions on structures and to select input ground motions for seismic structural analysis. This is the case, for example, in Italy where the new seismic code also requires the seismic input for nonlinear dynamic analysis to be selected on the basis of dominating events, for example, identified via disaggregation of seismic hazard. In the present study, the design earthquakes expressed in terms of representative magnitude (M), distance (R), and ε were investigated for a wide region in the southern Apennines, Italy. To this aim, the hazards corresponding to peak ground acceleration and spectral acceleration at 1 sec with a return period of 475 yr were disaggregated. For each of the disaggregation variables the shape of the joint and marginal probability density functions were studied. The first two modes expressed by M, R, and ε were extracted and mapped for the study area. The results shown provide additional information, in terms of source and ground-motion parameters, to be used along with the standard hazard maps to better select the design earthquakes. The analyses also allow us to assess how various frequency ranges of the design spectrum are differently contributed by seismic sources in the study area.

Description: Published

Description: 2979–2991

Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale

Description: JCR Journal

Description: reserved

Description: On September 6, 2002, aML =5.6 earthquake, occurring some tens of kilometres offshore from the Northern Sicilian coast (Southern Tyrrhenian Sea), slightly damaged the city of Palermo and surroundings (degree 6 in the European Macroseismic Scale 1998). The macroseismic investigation of the shock and a detailed study of effects of the main earthquakes which affected Palermo in the past have been performed in order to evaluate the seismic response of the city. Moreover, the comparison of the recent event, which is instrumentally constrained, with historical earthquakes allows us to infer new insights on the seismogenic sources of the area, that seem located offshore in the Tyrrhenian sea. In the last 500 years, Palermo has never been completely destroyed but has suffered effects estimated between intensities 6 and 8 EMS-98 many times (1693, 1726, 1751, 1823, 1940, 1968, 2002). The damage scenarios of the analysed events have shown that damage distribution is strongly conditioned by soil response in the different parts of the city and by a high building vulnerability, mainly in the historical centre and in the south-eastern zone of the modern city. As a matter of fact, Palermo has always suffered greater effects than those reported for other nearby localities. The hazard assessment obtained using observed site intensities has shown that the probability of occurrence for intensity 8 (the strongest intensity observed in Palermo) exceeds 99% for 550 years, while the estimated mean return period is 152 ± 40 years. These results, in connection with building vulnerability due to the urban expansion before the introduction of seismic code, suggest that the city is exposed to a relatively high seismic risk.

Description: Published

Description: 525-543

Description: partially_open

Description: Vengono presentate le stime di pericolosità sismica, in termini di intensità macrosismica, ottenute mediante l’approccio probabilistico proposto da Albarello e Mucciarelli (2002), basato sull’impiego dei dati documentari relativi agli effetti locali prodotti dai terremoti passati (storie sismiche di sito). I risultati forniti da questa procedura (approccio “di sito”), in termini di minimo valore di intensità caratterizzato da una probabilità di eccedenza inferiore al 10% in 50 anni (Iref), sono confrontati con quelli ottenuti sul territorio italiano tramite la metodologia “standard” di Cornell-McGuire. Per meglio comprendere i motivi delle differenze osservate tra le due stime e il ruolo di differenti basi informative, sono state prodotte diverse mappe di pericolosità. Stime di pericolosità a scala locale sono state inoltre effettuate nell’area dell’Etna dove, grazie a numerosi studi macrosismici di dettaglio, sono disponibili storie sismiche di sito particolarmente ricche.

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open

Description: A seismic rehabilitation program is being implemented to address the vulnerability of a large proportion of Italian building stock. A risk management framework, initially only for Italian school buildings, has been developed to assign priorities for the rehabilitation, and to give timescales within which retrofit or demolition must take place. Since it is not practical to carry out detailed assessment for around 60,000 Italian schools, the framework is a multiple-level procedure that aims to identify the highest-risk buildings based on filters of increasing detail, and reduces the size of the building inventory at each step. Finally, priorities and timescales are assigned based on vulnerability, seismic hazard, and building occupancy, within a general framework with parameters that must be assigned by the relevant authorities. The methodology is transparent, technically based, and flexible enough to be adapted for other building types or regions.

Description: DPC — Dipartimento della Protezione Civile

Description: Published

Description: 291-314

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: JCR Journal

Description: reserved

Description: Earthquake early warning systems (EEWS), based on real-time prediction of ground motion or structural response measures, may play a role in re- ducing vulnerability and/or exposure of buildings and lifelines. Indeed, seismologists have recently developed efficient methods for real-time es- timation of an event’s magnitude and location based on limited informa- tion of the P-waves. Therefore, when an event occurs, estimates of magni- tude and source-to-site distance are available, and the prediction of the structural demand at the site may be performed by Probabilistic Seismic Hazard Analysis (PSHA) and then by Probabilistic Seismic Demand Analysis (PSDA) depending upon EEWS measures. Such an approach contains a higher level of information with respect to traditional seismic risk analysis and may be used for real-time risk management. However, this kind of prediction is performed in very uncertain conditions which may affect the effectiveness of the system and therefore have to be taken into due account. In the present study the performance of the EWWS under development in the Campania region (southern Italy) is assessed by simu- lation. The earthquake localization is formulated in a Voronoi cells ap- proach, while a Bayesian method is used for magnitude estimation. Simu- lation has an empirical basis but requires no recorded signals. Our results, in terms of hazard analysis and false/missed alarm probabilities, lead us to conclude that the PSHA depending upon the EEWS significantly improves seismic risk prediction at the site and is close to what could be produced if magnitude and distance were deterministically known.

Description: Published

Description: 211-232

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: reserved

Description: Convenzione INGV-DPC 2004 – 2006 / Progetto S1 Proseguimento della assistenza al DPC per il completamento e la gestione della mappa di pericolosità sismica prevista dall'Ordinanza PCM 3274 e progettazione di ulteriori sviluppi

Description: Published

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open

Description: The supposed b-value spatial variability is the central topic of many scientific works dealing with forecasting modeling applications or geological correlations. If used for seismicity rates determination, the b-value plays an important role in probabilistic seismic hazard assessment, but how much does it influence PSHA? In the logic tree approach used for the new probabilistic seismic hazard map of Italy, named MPS04 (MPS Working Group, 2004), one of the sources of epistemic uncertainty considered was the procedure for computing seismicity rates. Two alternatives were adopted: 1) compute the activity rates for each binned magnitude class and 2) compute a Gutenberg-Richter (1944) distribution. In the logic tree branches where Gutenberg-Richter distribution was adopted, the corresponding bvalue was evaluated for each seismogenic zone: it spans between 0.63 and 2.01. After analysing the b-value variability in the Italian region, this work evaluates the impact of setting the b-value equal to 1 on the results of seismic hazard assessment in terms of PGA and energy release compared to the choices adopted for MPS04 (MPS Working Group, 2004).

Description: Published

Description: 59-76

Description: 4T. Sismicità dell'Italia

Description: N/A or not JCR

Description: open

Description: This work presents the results of a mineralogical and isotopic (18O, 13C, 87Sr/86Sr) study on xenoliths ejected during the famous 79AD Plinian eruption of Vesuvius. They are considered to be representative of the upper parts of the crystallizing margins of the magma chamber and also of the associated skarn shell. The aim of this study is to describe the thermometamorphic and metasomatic processes which took place at the 79AD magma chamber/wall-rock interface. The results of our research indicate that metasomatism of carbonate wall rocks of the 79AD Vesuvius magma chamber took place due to the infiltration of magmatic fluids, which were exsolved from the peripheral parts of the magma chamber itself. These fluids drive Fe, K, Si, Al and trace elements such as REE, Nb, U, Th, Zr, W, Sb, Pb extracted from the magma into the carbonate host-rocks, thus producing exoskarn. No evidence of later re-equilibrium with low temperature external fluids of meteoric origin was observed. This indicates that only the prograde early stage of skarn formation is recorded in these xenoliths.

Description: Published

Description: 1-10

Description: partially_open

Description: The development and implementation of an earthquake early warning system (EEWS), both in regional or on-site configurations can help to mitigate the losses due to the occurrence of moderate-to-large earthquakes in densely populated and/or industrialized areas. The capability of an EEWS to provide real-time estimates of source parameters (location and magnitude) can be used to take some countermeasures during the earthquake occurrence and before the arriving of the most destructive waves at the site of interest. However, some critical issues are peculiar of EEWS and need further investigation: (1) the uncertainties on earthquake magnitude and location estimates based on the measurements of some observed quantities in the very early portion of the recorded signals; (2) the selection of the most appropriate parameter to be used to predict the ground motion amplitude both in near-and far-source ranges; (3) the use of the estimates provided by the EEWS for structural engineering and risk mitigation applications. In the present study, the issues above are discussed using the Campania–Lucania region (Southern Apennines) in Italy, as test-site area. In this region a prototype system for earthquake early warning, and more generally for seismic alert management, is under development. The system is based on a dense, wide dynamic accelerometric network deployed in the area where the moderate-to-large earthquake causative fault systems are located. The uncertainty analysis is performed through a real-time probabilistic seismic hazard analysis by using two different approaches. The first is the Bayesian approach that implicitly integrate both the time evolving estimate of earthquake parameters, the probability density functions and the variability of ground motion propagation providing the most complete information. The second is a classical point estimate approach which does not account for the probability density function of the magnitude and only uses the average of the estimates performed at each seismic station. Both the approaches are applied to two main towns located in the area of interest, Napoli and Avellino, for which a missed and false alarm analysis is presented by means of a scenario earthquake: an M 7.0 seismic event located at the centre of the seismic network. Concerning the ground motion prediction, attention is focused on the response spectra as the most appropriate function to characterize the ground motion for earthquake engineering applications of EEWS.

Description: Published

Description: On line First

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: JCR Journal

Description: reserved

Description: Earthquake Early Warning Systems (EEWS), based on real-time prediction of ground motion or structural response measures, may play a role in reducing vulnerability and/or exposition of buildings and lifelines. In fact, recently seismologists developed efficient methods for rapid estimation of event features by means of limited information of the P-waves. Then, when an event is occurring, probabilistic distributions of magnitude and source-to-site distance are available and the prediction of the ground motion at the site, conditioned to the seismic network measures, may be performed in analogy with the Probabilistic Seismic Hazard Analysis (PSHA). Consequently the structural performance may be obtained by the Probabilistic Seismic Demand Analysis (PSDA), and used for real-time risk management purposes. However, such prediction is performed in very uncertain conditions which have to be taken into proper account to limit false and missed alarms. In the present study, real-time risk analysis for early warning purposes is discussed. The magnitude estimation is performed via the Bayesian approach, while the earthquake localization is based on the Voronoi cells. To test the procedure it was applied, by simulation, to the EEWS under development in the Campanian region (southern Italy). The results lead to the conclusion that the PSHA, conditioned to the EEWS, correctly predicts the hazard at the site and that the false/missed alarm probabilities may be controlled by set up of an appropriate decisional rule and alarm threshold.

Description: Published

Description: Geneva, Switzerland.

Description: open

Description: A new approach has been developed aiming at the probabilistic estimate of seismic hazard from the local seismic history. This is expressed in terms of seismic effects documented at the site during past earthquakes (macroseismic intensity) and thus a specific statistical treatment is required to take into account the peculiar character of macroseismic data that are discrete, ordinal and range-limited. The proposed procedure also allows the correct treatment of relevant uncertainty (ill-defined intensity values, local catalogue completeness, etc.) in the frame of a coherent distribution-free statistical approach. This methodology has been implemented in a free computer program (SASHA: Site Approach to Seismic Hazard Assessment) and applied to the seismic hazard estimation at the 8100 municipalities in Italy. The program also implements a probabilistic procedure to “translate” hazard estimates provided in terms of Intensity to other ground-shaking parameters (e.g. PGA): this “rescaling” procedure allows to com-pare the results coming from this approach with those provided by standard PSHA procedures. This comparison results of great importance at the sites where a relatively rich seismic history is available and it could provide a benchmark for different approaches to PSHA.

Description: Unpublished

Description: Hersonissos, Crete, Greece

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open

Description: We compare the results obtained from the modelling of EDM, GPS, levelling and tilt data measured in the first part of the 19911993 eruption at Etna to the InSAR data acquired during the second part. The geodetic changes are very marked in the first half of the eruption and constrain a deflation source located at a few kilometers of depth ( 3 km b.s.l.), in agreement with other independent geophysical evidence. SAR data, available during the second part of the eruption, were analysed for different time intervals in the second part of the eruption. The interpretation of SAR interferograms reveals a large-scale but less marked deflation of the volcano that could be caused by a deeper source. This second source is in accord with a second deeper anomaly revealed by recent seismic investigations. The combination of geodetic data modelling and SAR images suggests a complex plumbing system composed at least of two possible storage regions located at different depths.

Description: Published

Description: 1345-1357

Description: partially_open

Description: The recent eruption of Mount Etna (July 2001) offered the opportunity to analyze magma-derived volatiles emitted during preand syn-eruptive phases, and to verify whether their composition is affected by changes in volcanic dynamics. This paper presents the results of analyses of F, Cl and S in the volcanic plume collected by filter-packs, and interprets variations in the composition based on contrasting solubility in magmas. A Rayleigh-type degassing mechanism was used to fit the acquired data and to estimate Henryâ s solubility constant ratios in Etnean basalt. This model provided insights into the dynamics of the volcano. Abundances of sulfur and halogens in eruptive plumes may help predict the temporal evolution of an ongoing effusive eruption.

Description: -Gruppo Nazionale per la Vulcanologia.

Description: Published

Description: 1559

Description: partially_open

Description: The equilibrium between a 4-component H2O–CO2–SO2–H2S gas phase and a 13-component silicate liquid made of 10 major oxides plus dissolved H2O, CO2, and S, is investigated by means of calculations involving homogeneous reactions in the gas phase and heterogeneous gas–liquid saturation modeling based on classical Gibbs thermodynamics and Toop–Samis polymeric approach. Sulfur is assumed to be present in two different oxidation states in the gas (sulfur dioxide and hydrogen sulfide) and liquid (sulfide and sulfate ions) phase, implying a dependence of the equilibrium conditions on the redox state of the system. Sulfur-bearing solid phases and Fe–O–S immiscible liquid are not accounted for in the modeling. The thermodynamic model is an extension of the one presented in Moretti et al. [Moretti R., Papale P. and Ottonello, G., 2003. A model for the saturation of C–H–O–S fluids in silicate melts. In: Oppenheimer C., Pyle D.M., Barclay J. (eds.) Volcanic Degassing, Geol. Soc. London Spec. Publ., 213, 81–101.] to account for iron speciation at high pressure and dissolved water contents. The consequences on the equilibrium conditions of different assumptions concerning the effective redox buffer in magma are examined through calculations made on two different liquids of shoshonitic and rhyolitic composition, determining the equilibrium conditions on the basis of (i) constant ferric to ferrous mass ratio, (ii) constant hydrogen sulfide to sulfur dioxide fugacity ratio, and (iii) constant oxygen fugacity relative to a solid–gas buffer (DNNOF0.5). Following Giggenbach [Giggenbach, W.F., 1996. Chemical composition of volcanic gases. In: Scarpa R., Tilling R.I. (eds.) Monitoring and Mitigation of Volcano Hazards, Springer-Berlin, 202–226.], the first two buffers are expected to be effective in basaltic and rhyolitic magmas, respectively, according to the most abundant reservoir of redox couples represented by iron in basalts, and sulfur in rhyolite. The model results show strongly nonlinear dependence of the equilibrium compositions in the gas and liquid phases, as well as of the oxidation state of the system, on the assumed redox buffer. Furthermore, for each assumed redox buffer, the pressure dependence of phase composition and oxidation state of the system also shows strongly nonlinear trends. The largest compositional differences are shown by sulfur species; however, the concentrations of water and carbon dioxide in the two phases at equilibrium also show nonnegligible dependence on the redox conditions. For each assumed redox buffer, sulfur dioxide in the gas phase, and sulfate ions in the liquid phase, are found to be present in appreciable quantities or represent the dominating sulfur species even at the largest employed pressures approaching 500 MPa. The more reliable redox buffers represented by constant ferric to ferrous mass ratio for shoshonite, and constant hydrogen sulfide to sulfur dioxide fugacity ratio for rhyolite, show that oxygen fugacity paths during magma depressurization strongly deviate from those parallel to NNO. Therefore, the characterization of the oxidation state in depressurizing magmas on the basis of deviations from solid buffers (usually NNO or QFM) may not be appropriate.

Description: Published

Description: 265– 280

Description: partially_open

Description: We have developed a Bayesian method for the inversion of static ground deformations at volcanic areas.

Description: Published

Description: 935-946

Description: partially_open

Description: Measurements of CO2 flux from the ground were periodically carried out on the island of Vulcano (Aeolian Islands, Italy) between 1984 and 1994. Three high-flux areas were identified at the foot of the volcanic cone (La Fossa), either inside or very close to the main village. Effect of the choice of the sampling grid was evaluated. A different sampling grid resulted in similar distribution patterns, but with different CO2 fluxes. Therefore, the absolute estimate of the total flux from the investigated area includes a large degree of uncertainty, but repeated measurements with permanent sampling sites are accurate and can detect small changes. No correlation of the flux with atmospheric parameters was found at sites with high fluxes. Some periods characterized by high CO2 fluxes were observed, and a close correlation was found between the gas emissions from the ground and other geochemical and geophysical parameters such as temperature, chemical composition, steam, and SO2 flux from fumaroles, seismic energy release, and ground deformations. The results show that major temporal variations of diffuse CO2 flux are related to variations in volcanic activity.

Description: Gruppo Nazionale per la Vulcanologia CNR Italy.

Description: Published

Description: 219–228

Description: partially_open

Description: The city of Palermo (southern Italy) was severely damaged in the past by moderate-magnitude earthquakes located tens of kilometres offshore. The historical monumental heritage and the high density of population motivated large efforts for the seismic risk assessment. We present the geological and seismological studies performed in downtown Palermo as a study case to show how the complexity of an urban environment can be approached with multidisciplinary investigations. Downtown Palermo is characterized by sea deposits in the coastal zone and the alluvial deposits of two rivers (Papireto and Kemonia) of about 150 m width, which were buried and filled during the XVII century. The difficulty of surface geological surveys was compensated through an analysis of aerial photos and more than 2000 borehole data organized in the City-GIS of the Department of Geology and Geodesy of the University of Palermo. A previous study on the well-documented historical damage indicated the major role played by the two river valleys and the sea deposits in controlling the damage distribution, above the assumption of a fairly homogeneous vulnerability of the existing buildings in downtown. To test the feasibility of using ambient noise for recognizing the presence of alluvial deposits in a densely urbanized environment, a large microtremor measurement campaign was performed in Palermo across several profiles. The frequency peaks inferred from the horizontal-to-vertical spectral ratio were compared with numerical simulations to assess the seismic velocity profile and the soil stratigraphy. Moreover, noise data were analyzed through a statistical approach to establish a possible correlation between damage, resonance frequency and amplitude, and geology. After the moderate earthquake of September 6, 2002 (Mw=5.9, 50 km far away), the analysis of the aftershock sequence provided a well documented estimate of the variation of ground motion within the city in the case of linear soil response. Using these aftershocks we computed also synthetic accelerograms of the main shock through Empirical Green’s Functions that provided ground accelerations as large as 50 gals, consistently with the documented EMS-98 intensity. Synthetic accelerograms showed a large variability of horizontal ground motion within the city (a factor of 3 – 4) that confirms the role of local geology in causing an increase of the seismic hazard on sea and alluvial deposits. Finally, we discuss the comparison between the acceleration response spectra calculated for different soil categories and the design elastic spectra provided by EC8.

Description: Unpublished

Description: Lisbon, Portugal

Description: open

Description: After the 2002 earthquakes, that struck the southern Italy provinces of Campobasso (Molise) and Foggia (Apulia), the safety assessment of buildings has allowed to evaluate, for different building typologies, the damage level caused by the seismic event; in particular, the survey of the damaged cultural heritage was carried out by the Task Cultural Heritage of the Mixed Operating Centre (COM) in Larino (a village in the epicentral area), coordinated by the “Working Group for the Safeguard of the Cultural Heritage from Natural Risks” (Italy’s Gazzetta Ufficiale n. 116, 21 May 2001 - PCM-DPC Decree, 3 May 2001)”. For this survey activity, the churches were investigated with a specific form proposed by the same Working Group (Ministerial Decree n. 133, 23th January 2001), adopting different forms for other kinds of buildings. The surveyors were organized in teams, called NOPSA (Nuclei Operativi Patrimonio Storico Artistico), composed by officials of the Regional board of the Ministry of Cultural Heritage and Environmental Conservation (architects and art historians), an engineer and a Fire Brigade technician. The first phase of the safety assessment has been developed on the basis of the warnings received by the Larino COM, and most of the surveyed buildings were churches. The damage assessment of public or private buildings began, initially, near the earthquake epicentre (area 1 - IMCS between 6 and 8.5) and subsequently was carried out for all the villages from which inspection requests arrived. At the same time a vulnerability survey was carried out for the churches, using the II level form (Lagomarsino et al., 2004) proposed in the SAVE Project (“Updated Tools for the Seismic Vulnerability Evaluation of the Italian Real Estate and of Urban Systems” – http://gndt.ingv.it). The damage and vulnerability survey has allowed to verify and optimize the procedures for damage assessment immediately after a seismic event (emergency phase) and to obtain useful indications for the reconstruction phase. On the whole 379 monumental buildings in 101 Molise villages and 207 monumental buildings in 44 Apulia villages were investigated. Figure 1 shows the number of monumental buildings surveyed after the earthquakes for each Molise village, subdividing the region according to the seismic classification proposed by the recent Italian Seismic Code (OPCM n. 3274, 2003 – http://zonesismiche.mi.ingv.it).

Description: Unpublished

Description: First European Conference on Earthquake Engineering and Seismology (a joint event of the 13th ECEE & 30th General Assembly of the ESC) Geneva, Switzerland, 3-8 September 2006 Paper Number: 656

Description: open

Description: Earthquake Early Warning Systems (EEWS), based on real-time prediction of ground motion or structural response measures, may play a role in reducing vulnerability and/or exposition of buildings and lifelines. In fact, recently seismologists developed efficient methods for rapid estimation of event features by means of limited information of the P-waves. Then, when an event is occurring, probabilistic distributions of magnitude and source-to-site distance are available and the prediction of the ground motion at the site, conditioned to the seismic network measures, may be performed in analogy with the Probabilistic Seismic Hazard Analysis (PSHA). Consequently the structural performance may be obtained by the Probabilistic Seismic Demand Analysis (PSDA), and used for real-time risk management purposes. However, such prediction is performed in very uncertain conditions which have to be taken into proper account to limit false and missed alarms. In the present study, real-time risk analysis for early warning purposes is discussed. The magnitude estimation is performed via the Bayesian approach, while the earthquake localization is based on the Voronoi cells. To test the procedure it was applied, by simulation, to the EEWS under development in the Campanian region (southern Italy). The results lead to the conclusion that the PSHA, conditioned to the EEWS, correctly predicts the hazard at the site and that the false/missed alarm probabilities may be controlled by set up of an appropriate decisional rule and alarm threshold.

Description: Published

Description: open

Description: We report here on the real-time measurement of CO2 and SO2 concentrations in the near-vent volcanic gas plume of Mount Etna, acquired by the use of a field portable gas analyzer during a series of periodic field surveys on the volcano’s summit. During the investigated period (September 2004 to September 2005), the plume CO2/SO2 ratio ranged from 1.9 to 10.8, with contrasting composition for Northeast and Voragine crater plumes. Scaling the above CO2/SO2 ratios by UV spectroscopy determined SO2 emission rates, we estimate CO2 emission rates from the volcano in the range 0.9–67.5 kt d 1 (average, 9 kt d 1). About 2 kt of CO2 were emitted daily on average during quiescent passive degassing, whereas CO2 emission rates from Etna’s summit were 10–40 times larger during the 2004–2005 effusive event (with a cumulative CO2 release of 3800 kt during the 6 months of the eruption). Such a syneruptive increase, ascribed to the replenishment of the shallow (〈6 km) volcanic plumbing system by CO2-rich (0.25 wt %) more primitive magmas, supports the potential of CO2 output rates as key parameters for volcanic hazard assessment.

Description: Published

Description: B09207

Description: JCR Journal

Description: reserved

Description: Prior to 2003 the Italian building code, established in 1974, was mostly based on working stress design. The zonation that guided its application was made up in 1981 using a semi-quantitative, mainly seismological approach; it was enforced in 1984 and left about 2/3 of the territory without seismic provisions. In 1998 a new zonation was proposed but never adopted. The 2002 Mw5.7 earthquake in Molise (Southern Italy) caused the collapse of a school and the death of 26 children. The school was built in an area where seismic provisions were not applied, although the zonation proposed in 1998 assigned it to the second zone. The earthquake triggered a process that led in a few months to a new set of seismic provisions

Description: Unpublished

Description: San Francisco

Description: open

Description: Published

Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce

Description: open

Description: An extensive geochemical survey on the fluids released by the volcanic/geothermal system of Methana was undertaken. Characterization of the gases was made on the basis of the chemical and isotopic (He and C) analysis of 14 samples. CO2 soil gas concentration and fluxes were measured on the whole peninsula at more than 100 sampling sites. 31 samples of thermal and cold groundwaters were also sampled and analysed to characterize the geochemistry of aquifers. Anomalies referable to the geothermal system, besides at known thermal manifesta-tions, were also recognized at some anomalous degassing soil site and in some cold groundwater. These anomalies were always spatially correlated to the main active tectonic system of the area. The total CO2 output of the volcanic system has been preliminary estimated in about 0.2 kg s-1. Although this value is low compared to other volcanic systems, anomalous CO2 degassing at Methana may pose gas hazard problems. Such volcanic risk, although restricted to limited areas, cannot be neglected and further studies have to be undertaken for its better assessment

Description: Published

Description: 712-722

Description: N/A or not JCR

Description: open

Description: After the 2002 Molise earthquake, a wide survey of the damage and the seismic vulnerability of the churches was carried out, using specific forms extensively tested and recently acknowledged at a national scale (G.U. 07/03/2006). This approach has allowed one to compare the observed and the expected medium damage, calculated through vulnerability curves correlated to the specific form used. This comparison has enabled to evaluate inhomogeneous values in some cases, pointing out how the surveyed damage could not be put down just to a structural lack of the building. Studying the sites morphology for the churches located on the ridges, it was observed a damage level always greater than expected. To study the influence of the local amplification phenomena due to the topography, it has been analyzed some churches damaged by the Appennino Abruzzese (1984) and Molise (2002) earthquakes. These churches are located on the ridges top, with slope in-clination alfa≥15°, height H≥30m and characterized by homogeneous lithological subsoil, almost to consider it having an elastic behavior under dynamical stress. Taking into account this hazard increase inside a vulnerability analyses (based on a macroseismic or a mechanical approach), it has been proposed a double approach, validated through local seismic response (RSL) modeling of the ground (estimation of amplification factors and of elastic response spectra) and through the seismic response of the macroelements, damaged by the reference earth-quake (linear and not-linear kinematic analysis). Through the vulnerability analysis based of the macroseismic approach, the influence of the site morphology on the building behavior has been preliminary defined by a vulnerability modifier (deltaVml), that represents an additional parameter to reach the equivalent value between the surveyed and the expected damage. The study of the amplification effects has been performed using the BEM numerical analysis; the results are represented by the amplification factors (Fa), defined as the ratio between the spectral intensity of output and input, considering the range period of 0.1s-0.5s, and the corresponding elas-tic response spectra: they confirm the results of the macroseismic approach. Considering the mechanical approach, two churches have been examined in detail (S Pietro in Vincoli at Castellino del Biferno and S. Michele Arcangelo at Campolieto): the kinematic analyses have been performed applied the calculated amplified and not-amplified response spectra (considering the earthquake 2002) and the design response spectrum. The analyses show that the results obtained applying the calculated amplified response spectrum are better correlated to the surveyed damage of the churches than the results obtained applying the not-amplified response spectrum.

Description: Published

Description: Pisa, Italia

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: open

Description: The damage and vulnerability survey of the monumental buildings, damaged by the 2002 earthquake in the Molise Region, has allowed singling out of a correlation between the observed damage of the churches and their morphological site conditions. The vulnerability model connected to the survey methodology provides an evaluation of the expected mean damage. Comparison with the observed damage determined the introduction of a local morphological behaviour modifier, able to take into account the vulnerability increase due to the site effects. In order to validate the previous results, a numerical 2-D analysis of the seismic local response has been performed. In particular, a numerical code, working with boundary elements, has been applied to the analyzed situations. The results, in terms of pseudo-acceleration response spectra and amplification factors, allow one to compare the numerical and the observed analyses. This comparison shows good agreement and allows one to find some correlations between the geometric characteristics of the sites, the values of the amplification coefficients and the damage mechanism activated.

Description: Published

Description: Thessaloniki, Greece

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: 4.2. Scenari e mappe di pericolosità sismica e danno

Description: open

Description: The aim of this work is to produce a prototype of an Integrated Geographic Informative System designed to characterize the seismic vulnerability of the municipalities of the Benevento province. The developed GIS model algorithm is based on a systemic methodology which accounts for interactions among the several factors involved into the system. The implemented algorithm allows to estimate a vulnerability index, which in turn led to the creation of vulnerability maps. This System, which could be enriched with new thematic data will provides the basis for future researches in the field and make available to local decision-makers, agencies and community planners basic information to be used in managing the seismic risk.

Description: Published

Description: Centro Congressi Lingotto, Torino

Description: open

Description: For early-warning applications in particular, the reliability and efficiency of rapid scenario generation strongly depend on the availability of reliable strong ground-motion prediction tools. If shake maps are used to represent patterns of potential damage as a consequence of large earthquakes, attenuation relations are used as a tool for predicting peak ground-motion parameters and intensities. One of the limitations in the use of attenuation relations is that these have only rarely been retrieved from data collected in the same tectonic environment in which the prediction has to be performed. As a consequence, strong ground motion can result in underestimations or overestimations with respect to the recorded data. This also holds for Italy, and in particular for the Southern Apennines, due to limitations in the available databases, both in terms of distances and magnitude. Moreover, for “real-time” early-warning applications, it is important to have attenuation models for which the parameters can be easily upgraded when new data are collected, whether this has to be done during the earthquake rupture occurrence or in the post-event, when all the strong motion waveforms are available. Here we present a strong-motion attenuation relation for early-warning applications in the Campania region (Southern Apennines), Italy. The model has a classical analytical formulation, and its coefficients were retrieved from a synthetic strong-motion database created by using a stochastic approach. The input parameters for the simulation technique were obtained through the spectral analysis of waveforms of earthquakes recorded by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) network for a magnitude range Md (1.5,5.0) in the last fifteen years, and they have been extrapolated to cover a larger range. To validate the inferred relation, comparisons with two existing attenuation relations are presented. The results show that the calibration of the attenuation parameters, i.e., geometric spreading, quality factor Q, static stress drop values along with their uncertainties, are the main concern.

Description: Published

Description: 133-152

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: reserved

Description: In the framework of an ongoing project financed by the Campania Region, a prototype system for seismic early and post-event warning is being developed and tested, based on a dense, wide dynamic seismic network (ISNet) and under installation in the Apennine belt region. This paper reports the characteristics of the seismic network, focussing on the required technological innovation of the different seismic network components (data-logger, sensors and data communication). To ensure a highly dynamic recording range, each station is equipped with two types of sensors: a strong-motion accelerometer and a velocimeter. Data acquisition at the seismic stations is performed using Osiris-6 model data-loggers made by Agecodagis. Each station is supplied with two (120 W) solar panels and two 130 Ah gel cell batteries, ensuring 72-h autonomy for the seismic and radio communication equipment. The site is also equipped with a GSM/GPRS programmable control/alarm system connected to several environmental sensors (door forcing, solar panel controller, battery, fire, etc) and through which the site status is known in real time. The data are stored locally on the hard-disk and, at the same time, continuously transmitted by the SeedLink protocol to local acquisition/analysis nodes (Local Control Center) via Wireless LAN bridge. At each LCC site runs a linux Earthworm system which stores and manages the acquired data stream. The real-time analysis system will perform event detection and localization based on triggers coming from data-loggers and parametric information coming from the other LCCs. Once an event is detected, the system will performs automatic magnitude and focal mechanism estimations. In the immediate post-event period, the RISSC performs shaking map calculations using parameters from the LCCs and/or data from the event database. The recorded earthquake data are stored into an event database, to be available for distribution and visualization for further off-line analyses. The seismic network will be completed in two stages: • Deployment of 30 seismic stations along the southern Apennine chain (to date almost completed) • Setting up a carrier-class radio communication system for fast and reliable data transmission, and installation of 10 additional seismic stations.

Description: Published

Description: 325 - 341

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: reserved

Description: One of the main requirements by OPCM 3274 was the transparency of the PSH assessment (to be achieved through the publication of the procedure adopted and the data used) so that anyone would be able to verify the consistency of the results and follow the most updated state-of-the-art. In addition, OPCM 3519 stated that the seismic hazard data had to be made officially available through a dedicated website (http://zonesismiche.mi.ingv.it). The web site supplies the seismic hazard data expressed in terms of peak ground acceleration (ag) with 10% of exceedance probability in 50 years as well as their variability stated in terms of the 16th and 84th percentiles. In addition, the same website can supply even the scientific technical documentation as well as the input data used in such a project. As integration of these contents, a second web site (http://esse1.mi.ingv.it) has been developed with the aim to make available all the information about the organization of the S1 project (work program, tasks organization, list of the deliverables, progress state), underlying the most important results and for an immediate fruition by the project endusers. For this purpose a webGis tool has been carried out to visualize and query interactive hazard maps of the Italian territory, represented through various shaking parameters (values of peak ground acceleration and elastic response spectra for a given T period).

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open

Description: Vengono presentate nuove relazioni empiriche, definite per il territorio italiano, per la stima dell’intensità in un dato sito a partire da informazioni epicentrali o relative a località vicine. Queste relazioni, espresse in forma probabilistica e quindi direttamente utilizzabili per la stima della pericolosità sismica, condividono la stessa formalizzazione e la medesima base informativa. In particolare, sono state seguite tre diverse strategie: le prime due hanno portato alla definizione di una relazione di attenuazione per la stima dell’intensità al sito da dati epicentrali utilizzando una forma parametrica rispettivamente Gaussiana e Binomiale; la terza analisi è stata invece mirata a definire le modalità di “correzione” del valore locale di intensità, dedotto dalle informazioni epicentrali, con dati di risentimenti osservati in località vicine al sito in esame.

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

Description: 5.1. TTC - Banche dati e metodi macrosismici

Description: open

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open

Description: Unpublished

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open

Description: The last strong earthquake that occurred in the southern Apennines, the Irpinia earthquake on 23 November 1980 (M 6.9), was characterized by a complex rupture mechanism that ruptured three different faults (Bernard and Zollo 1989). This earthquake was well studied, and the quantity of data available has allowed a very detailed definition of the geometry and mechanisms of faults activated during this seismic event (Westaway and Jackson 1987; Pantosti and Valensise 1990). Even more than 20 years after the main event, the seismotectonic environment that contains the fault system on which the 1980 earthquake occurred shows continued background seismic activity including moderate-sized events such as the 1996 (M 5.1), 1991 (M 5.1) and 1990 (M 5.4) events. Moreover, the locations of the microearthquakes (taken from the database of the Istituto Nazionale di Geofisica e Vulcanologia, INGV) define an epicentral area with a geometry and extent surprisingly similar to that of the 1980 earthquake and its aftershocks (figure 1A). These simple observations suggest that it may be possible to study the preparation cycles of strong earthquakes on active faults by studying the microseismicity between seismic events. With this in mind, a seismic network of large dynamic range was planned and is now in an advanced phase of completion in the southern Apennines. Called ISNet (Irpinia Seismic Network), it is equipped with sensors that can record high-quality seismic signals from both small-magnitude and strong earthquakes, from which it will be possible to retrieve information about the rupture process and try to understand the scaling relationships between small and large events. Due to its high density, wide dynamic range, and advanced data-acquisition and data-transmission technologies, the network is being upgraded to become the core infrastructure of a prototype system for seismic early warning and rapid post-event ground-shaking evaluation in the Campania region, which has seismic hazard that ranks among the highest in Italy (Cinti et al. 2004). ISNet will be devoted to real-time estimation of earthquake location and magnitude and to measuring peak ground-motion parameters so as to provide rapid ground-shaking maps for the whole of the Campania region. The information provided by ISNet during the first seconds of a potentially damaging seismic event can be used to activate several types of security measures, such as the shutdown of critical systems and lifelines (Iervolino et al. 2006). The implementation of a modern seismic network involves many different research and technological aspects related to the development of sophisticated data management and processing. The communication systems need to rapidly generate useful, robust, and secure alert notifications. Here we provide a general technical and seismological overview of ISNet's complex architecture and implementation.

Description: Published

Description: 622-634

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: JCR Journal

Description: reserved

Description: The Peloritani Mts. (NE Sicily) are characterized by frequent seismicity. Between 1994 and 2006 more than 1000 earthquakes (1.0≤ML≤3.3) occurred, mostly as highly clustered swarms located at shallow depth near the villages of Castroreale and Rodì Milici (western part of Peloritani Mts.). The same area is also characterized by some geothermal springs and gas vents. Using a multidisciplinary approach, data were collected on the tectonic setting, seismicity pattern and geochemical characteristics of fluid emissions, with the aim of understanding the process of earthquake swarm generation beneath the investigated area. Most of the gases emitted in the study area, in terms of focused and/or diffuse gas emissions often associated with thermal fluids, is of mantle origin, as shown by their He isotopes ratio. On approaching the surface, deep gases interact strongly with local aquifers. An estimate of both the surface efflux of mantle-derived gases measured in focused emissions and of the P–T conditions of fluids in the local crust point to a pressurised gas source that would be located at depth of 7–12 km, corresponding to the range of hypocentral depths of seismic swarms. The complex network of tectonic structures in the area would act as high-permeability pathways for the migration of sub-crustal fluids towards the surface. This scenario could be compatible with a close interplay between pressurised mantle fluids at depth, nucleation of earthquakes due to higher-thanhydrostatic pore pressure and release of mantle-derived gases at the surface. This sequence would be repeated in time, thus producing the observed cycles in the local seismic activity.

Description: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Catania; Istituto Nazionale di Geofisica e Vulcanologia, sezione di Palermo

Description: Published

Description: 795-806

Description: 4.5. Degassamento naturale

Description: JCR Journal

Description: reserved

Description: Abstract A semi-permanent GPS network of about 30 vertices: Victoria Land Network for DEFormation control (VLNDEF) has been set up since Austral summer 1998 at Terra Nova Bay (TNB) near Ross Sea in Antarctica. A permanent GPS station TNB1 based on dual frequency Ashtech P-code GPS receiver with a Choke Ring Antenna has been installed on a bedrock monument in October 1998 and has recorded continuously up to the present. The GPS network has been routinely surveyed every two summers using high quality dual frequency GPS receivers; data, metadata and solutions are available to the scientific community at (http://www.geodant.unimore.it). In this paper we present the results of a distributed session approach applied to processing GPS data of the VLNDEF network, and based on Gamit/Globk 10.3 GPS analysis software. An improved reference frame definition was implemented using Globk package in order to compute Antarctic intra-plate residual velocities and to invert the strain field from GPS data in this region.

Description: Scientific Committee on Antarctic Research (SCAR) International Arctic Science Committee (IASC)

Description: Published

Description: St. Petersburg, Russia

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: reserved

Description: Six hundred and sixty-seven water samples were collected from public drinking water supplies in Sicily and analysed for electric conductivity and for their Cl-, Br- and F- contents. The samples were, as far as possible, collected evenly over the entire territory with an average sampling density of about one sample for every 7600 inhabitants. The contents of Cl- and Br-, ranging between 5.53 and 1302 mg/l and between 〈 0.025 and 4.76 mg/l respectively, correlated well with the electric conductivity, a parameter used as a proxy for water salinity. The highest values were found both along the NW and SE coasts, which we attributed to seawater contamination, and in the central part of Sicily, which we attributed to evaporitic rock dissolution. The fluoride concentrations ranged from 0.023 to 3.28 mg/l, while the highest values (only 3 exceeding the maximum admissible concentration of 1.5 mg/l) generally correlated either with the presence in the area of crystalline (volcanic or metamorphic) or evaporitic rocks or with contamination from hydrothermal activity. Apart from these limited cases of exceeding F- levels, the waters of public drinking water supplies in Sicily can be considered safe for human consumption for the analysed parameters. Some limited concern could arise from the intake of bromide-rich waters (about 3% exceeding 1 mg/l) because of the potential formation of dangerous disinfection by-products.

Description: Published

Description: 303-313

Description: 4.4. Scenari e mitigazione del rischio ambientale

Description: JCR Journal

Description: reserved

Description: È ormai ampiamente riconosciuto che la risposta sismica locale ha una sensibile influenza su distribuzione ed amplificazione dello scuotimento sismico e, conseguentemente, sul danneggiamento indotto dai terremoti. Nel lavoro di tesi, dal titolo “Analisi della Risposta Sismica Locale di San Giuliano di Puglia”, il candidato presenta uno studio molto ampio ed approfondito della risposta sismica del centro urbano che rappresenta finora la case history più documentata e significativa in Italia. Il lavoro di ricerca è inquadrato nel “Progetto S3 - Scenari di scuotimento in aree di interesse prioritario e/o strategico” promosso dall’Istituto Nazionale di Geofisica e Vulcanologia (INGV) per conto del Dipartimento della Protezione Civile (DPC), coordinato dalla Dr.ssa Francesca Pacor (INGV, Milano) e dal Prof. Marco Mucciarelli (Università della Basilicata). Il Progetto di ricerca si pone come obiettivo generale l’analisi di scenari di scuotimento e di danno in alcune aree italiane, nel caso di accadimento del terremoto massimo credibile (Maximum Credible Earthquake). Tra le aree di validazione è individuata quella di San Giuliano di Puglia, particolarmente danneggiato dalla sequenza sismica del Molise nel 2002, il cui vento principale (31 ottobre) è caratterizzato da una magnitudo momento pari a 5.8. Nell’area sono presenti diversi centri abitati, tra i quali San Giuliano di Puglia che, sebbene non fosse meno distante di altri dagli epicentri, è stato quello maggiormente danneggiato. Infatti, dopo gli eventi sismici, a San Giuliano di Puglia è stato osservato un grado di danneggiamento pari al VIII-IX grado sulla base della scala MCS, mentre negli altri Comuni la stima è stata al limite pari al VII (Stucchi et al., 2007). Il motivo di tale discrepanza è da ricercarsi negli importanti fenomeni di amplificazione sismica locale che hanno interessato le aree di più recente costruzione di San Giuliano di Puglia; queste sono state edificate, a partire dagli anni ’40, su un deposito di marne argillose di spessore pari ad alcune centinaia di metri. Tale deposito è a contatto con una formazione flyschoide, affiorante al di sotto del nucleo originario dell’abitato, dove è stato osservato un danneggiamento di grado inferiore. Dopo un’analisi preliminare della letteratura con riferimento a casi di studio nazionali che internazionali di carattere simile, la prima parte del lavoro di ricerca è dedicata allo studio della pericolosità sismica del sito, con riferimento a dati storici e, soprattutto, strumentali, acquisiti nel corso della recente sequenza. A tal fine, sono state analizzate le registrazioni della rete accelerometrica mobile installata da DPC nel centro urbano di San Giuliano di Puglia; tali registrazioni, interpretate in termini di fattori di amplificazione e rapporti spettrali, hanno permesso di verificare amplificazioni sismiche molto elevate nell’intero campo di frequenze in cui può essere ascritto il patrimonio edilizio del paese. Nell’ambito del Task 1 del Progetto S3, sono stati esaminati circa 2000 sismogrammi registrati dalla RAN (Rete Accelerometrica Nazionale) e dalle reti mobili installate nell’area epicentrale alcuni giorni dopo il mainshock. Queste analisi hanno consentito la calibrazione di leggi di attenuazione specifiche per l’area di studio (Luzi et al., 2006) e la simulazione numerica dell’evento del 31 ottobre (Franceschina et al., 2006). La seconda parte della tesi ha riguardato la definizione del modello geologico di sottosuolo per l’analisi di risposta sismica locale. I diversi studi geologici in merito (cfr. Baranello et al., 2003; Melidoro, 2004 e Guerricchio, 2005; Giaccio et al., 2004; Strollo et al., 2006) suggeriscono diverse ipotesi in merito alla morfologia profonda delle formazioni geologiche principali, il flysch di Faeto e le marne argillose di Toppo Capuana. Queste corrispondono, in buona sostanza, a diversi andamenti in profondità del contatto tra formazione argillo-marnosa ed il substrato flyschoide, identificati con altrettanti modelli geometrici di sottosuolo (basin, wedge, anvil). Tale fattore risulta fortemente influente sulla risposta sismica locale alle basse frequenze. Le ipotesi sono state verificate con riferimento ai risultati delle indagini geofisiche profonde, eseguite nell’area di San Giuliano di Puglia nell’ambito del Progetto S3; queste sono consistite in 3 inversioni tomografiche geoelettriche (Piscitelli, 2007), una campagna gravimetrica di dettaglio (Palmieri et al., 2006) e 2 linee sismiche a riflessione (Böhm, 2007). Sempre nell’ambito del Progetto S3, i risultati di queste indagini hanno consentito la costruzione di un modello geologico strutturale 3D dell’area (Caputo et al., 2007). La terza parte ha riguardato la definizione del modello geotecnico di sottosuolo per l’analisi di risposta sismica locale. Si è provveduto alla raccolta ed analisi di tutte le indagini geotecniche eseguite nel centro abitato, con particolare riferimento alla campagna del DPC per conto della Procura di Larino (Baranello et al., 2003), che ha consentito un’adeguata caratterizzazione geotecnica dell’unità argillosa. Durante questa campagna, nel 2003, sono state eseguite 11 prove down-hole e 3 prove cross-hole spinte anche oltre i 30 m di profondità, e, sui campioni di terreno prelevati, diversi laboratori hanno eseguito, oltre alle usuali prove di classificazione, numerose prove di compressione edometrica e isotropa, triassiali non drenate e di taglio torsionale ciclico e dinamico (Silvestri et al., 2006). I parametri meccanici attribuiti all’unità flyschoide provengono invece un’unica prova down-hole, eseguita nel corso della vasta campagna geognostica (2004-5) per la ricostruzione del paese. Il gran numero di sondaggi nell’intero centro urbano ha permesso una descrizione molto dettagliata della stratigrafia delle marne argillose di Toppo Capuana, il cui spessore più superficiale (mediamente fino a circa 10 m di profondità), si presenta caratterizzato da un alto grado di weathering e da un sensibile contrasto di impedenza sismica con le sottostanti argille intatte. L’eterogeneità della stratigrafia in direzione verticale ed orizzontale è stata rappresentata con diversi livelli di dettaglio, cioè assimilando la formazione superficiale ad un materiale omogeneo, oppure suddiviso in due strati, con spessori costanti oppure considerandone la variabilità con criteri geostatistici; tale approccio ha permesso di valutare l’influenza sull’amplificazione delle frequenze medio alte (oltre i 5 Hz) del dettaglio stratigrafico nella caratterizzazione dell’unità argillosa degradata. Nella quarta parte, il candidato presenta i risultati delle simulazioni numeriche 2D agli elementi finiti (codice QUAD4M), eseguite allo scopo di confrontare le diverse ipotesi formulate sull’andamento del bedrock e sulla stratigrafia superficiale, e validarle in base alle registrazioni strumentali. Come moti di riferimento sono state assunte due registrazioni della rete accelerometrica mobile di San Giuliano di Puglia, effettuate sulla formazione flyschoide nel corso degli aftershocks occorsi il 12 novembre (M=5.2) ed il 2 dicembre (M=4.0). Lo scuotimento in superficie simulato dalla modellazione numerica è confrontato, in termini sia di parametri sintetici del moto (accelerazioni di picco, intensità di Housner), sia di spettri di risposta, con le rispettive registrazioni eseguite alla superficie dell’unità argillosa e del flysch. L’ultima parte della tesi descrive lo scenario di scuotimento e di danno nel centro abitato indotto dal mainshock del 31 ottobre. Le simulazioni numeriche dello scuotimento sono state eseguite sui modelli di sottosuolo 2D elaborati lungo una sezione che attraversa l’asse longitudinale del centro urbano e validati nella fase precedente. I parametri del moto sono stati confrontati sia con quelli ottenuti tramite analisi 3D con il metodo degli elementi pseudo-spettrali (FPSM) lungo la medesima sezione (Klin e Priolo, 2007), e raffrontati con le amplificazioni registrate dalle stazioni accelerometriche mobili di San Giuliano di Puglia durante le scosse di assestamento. Le distribuzioni del danno corrispondenti alle analisi 2D e 3D sono state elaborate a partire dallo scuotimento, attraverso una correlazione tra l’intensità di Housner e quella macrosismica, espressa secondo la scala MCS (Mucciarelli et al., 2007). Gli scenari di danno così ottenuti hanno mostrato un buon accordo con quello osservato all’indomani della crisi sismica da Dolce et al. (2004). I risultati degli studi interdisciplinari sul centro urbano di San Giuliano di Puglia hanno quindi rappresentato una favorevole occasione per mettere a punto metodologie di previsione numerica di risposta sismica locale, evidenziandone la sensibilità a fattori geometrici e meccanici. La ricerca ha offerto inoltre la possibilità di esprimere i risultati di tali simulazioni in termini di grandezze significative per la rappresentazione del danno ai manufatti.

Description: Università della Calabria (Prof. Francesco Silvestri) - DPC-INGV (Progetto S3, 2004-2006 - coordinatori: Dott.ssa F. Pacor e Prof. M. Mucciarelli)

Description: Unpublished

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: open

Description: Tra tutte le strutture portuali censite all’interno del Programma di Ricerca “Progettazione sismica di strutture portuali marine” si sceglie il porto di Ancona come caso particolare per una valutazione deterministica di pericolosità e rischio sismico. Ancona, infatti, essendo uno dei principali porti in Italia per importanza del volume di scambio, costituisce un caso rappresentativo della situazione italiana per aree a medio-alta pericolosità sismica. Attraverso lo studio del caso di Ancona si é cercato di definire un procedimento per la valutazione del rischio generalmente riproducibile. Infatti, affinché questo metodo di investigazione sia facilmente replicabile per tutti i porti italiani, esso viene articolato a diversi livelli di dettaglio, in funzione dei dati e delle risorse disponibili. Particolare attenzione è stata posta nel valutare l’influenza sulla stima del danno per i diversi livelli di scuotimento. La ricerca viene sviluppata secondo i seguenti punti: i) scelta dell’evento (o degli eventi) di riferimento; ii) stima degli scenari di scuotimento con riferimento a suolo rigido, attraverso valutazioni empiriche e simulazioni avanzate, e valutazione della variabilità dei parametri del moto; iii) valutazione degli effetti di amplificazione geologica, stima del potenziale di liquefazione e dei cedimenti del terreno; iv) individuazione dei fattori per la valutazione del rischio (valutazione combinata di pericolosità , esposizione e vulnerabilità degli elementi) e infine v) valutazione del danno atteso.

Description: Eucentre, DPC.

Description: Published

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: open

Description: The soil CO2 flux on Mt. Etna as recorded by the ETNAGAS network (an automatic system for measuring soil CO2 flux and meteorological parameters) started to increase strongly about 5 months prior to the onset of the 2004–2005 eruption and decreased a few months before the end of the eruption. Time delays in the occurrences of anomalies in soil CO2 flux at different sites in the geochemical network constrain the relationship between soil CO2 flux distributions and the tectonic framework of Etna volcano. The anomalies observed before the 2004–2005 eruption support the intrusion of new undegassed magma into the upper feeding system of the volcano (〈20 km below sea level). Magma subsequently rose slowly in the volcano conduits, thereby triggering the onset of the 2004–2005 eruption. The time delays in the occurrences of anomalies in combination with spectral analysis indicate the importance of tectonic and volcanotectonic structures in driving the ascent of deep gases within the crust. Moreover, greatest amplitude pulsations of the low-frequency components of the CO2 flux signals were correlated with the paroxystic activities of the 2004–2005 eruption. This study confirms that CO2 flux variation is a useful indicator for volcanic activity in the surveillance of the Mt. Etna and similar basaltic volcanoes.

Description: Dipartimento Protezione Civile Ministero degli Interni

Description: Published

Description: B09206

Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani

Description: JCR Journal

Description: reserved

Description: Le reti permanenti GPS costituiscono una importante risorsa per una serie di studi tecnologici e scientifici. La carenza di conoscenze in studi di tettonica attiva, che comprendono anche la parte di sismologia come l'accumulo di deformazione sulle faglie, è stata a lungo frenata dalla mancanza di reti permanenti GPS sufficientemente dense distribuite su tutto il territorio nazionale. In particolare, la definizione di una placca Adriatica e la sua terminazione meridionale sono ancora materia di dibattito (Oldow et al., 2002; Battaglia et al. 2004). Inoltre, di recente, alcuni importanti lavori (Hollenstein, et al. 2004; D'Agostino and Selvaggi; Serpelloni et al. 2005) hanno mostrato che valori di deformazione molto più alti di quanto si pensava prima sono stati effettivamente riscontrati nella nostra regione e che solo l'uso di una rete densa di stazioni, quindi di un campionamento ad alta densità nelle aree dove sono maggiori le velocità relative, permette di osservare in modo corretto il rilascio, o accumulo, di deformazione. Infine, il contributo della geodesia alla sismologia sta diventando sempre più importante sia nella definizione del rilascio cosismico durante un terremoto e sia nell'osservazione e modellazione dell'accumulo intersismico di deformazione elastica su faglie attive. Da qualche anno, l'Istituto Nazionale di Geofisica e Vulcanologia (INGV) ha impiegato notevoli risorse e sforzi per rispondere a tali temi scientifici. Selvaggi et al. (2006) hanno gettato le basi e mostrato i primi sviluppi di una rete GPS permanente, la Rete Integrata Nazionale GPS (RING), creata con l'obiettivo di dare un forte contributo scientifico ai temi sopra citati La rete RING (Fig. 1a), nella sua completezza, rappresenta ad oggi non solo un punto di riferimento per studi di carattere scientifico ma anche una robusta infrastruttura tecnologica e informatica per l'archiviazione dei dati GPS per diverse altre reti locali e regionali (Regione Puglia, Regione Friuli, Leica Geosystems). Tali reti, contribuiscono quotidianamente all'acquisizione, all'interno di un server, di dati per un totale di oltre 300 stazioni distribuite sul territorio nazionale (Fig. 1b). Se, poi, si considera anche l'aspetto del processamento dei dati GPS, l'utilizzo di dati GPS appartenenti ad altre reti (locali, regionali o anche esterne al territorio italiano) fa sì che ogni analista utilizzi i dati, in media, di circa 650 stazioni GPS permanenti al giorno.

Description: Published

Description: L'Aquila - Italia

Description: 1.9. TTC - Rete GPS nazionale

Description: reserved

Description: In this work the results of a quick microtremor survey performed in the municipalities situated in the epicentre area of the Ml 5.2 2004 Salò earthquake (North Italy) are presented. The aim of this study is to understand if the large amount of damage caused by the event (about 215 millions of euros only in the areas near to the epicenter) is correlated more to the local surface geology conditions or to the vulnerability of ancient Italian historical centers. A preliminary seismic zonation was carried out in 5 villages including about 30 measurements of microtremors analysed by the Nakamura technique (hereinafter HVNR). The points of measurement were carefully selected considering sites located both near damaged buildings and over different local geology conditions (alluvium deposits, fluvial-glacial deposits, debris fans and rock). In order to strengthen the HVNR results and to evaluate the reliability of the Nakamura analysis, a comparison with spectral ratios calculated on earthquakes (hereinafter HVSR) recorded at the strong motion station of Vobarno was made. In general, the outcomes of the survey highlight a possible correlation between local geology conditions and ground motion amplification for different frequency bands. In order to check if this evidence is linked with the damage, a series of macroseismic intensities values were collected for different zones of the investigated area, and a non parametric correlation approach was used to establish a possible correlation between damage and ground motion amplification for selected frequency bands. The results show, from a statistical point of view, that in the area surrounding the epicenter of the 24 November 2004 mainshock, the damage pattern is not strongly dependent upon the local surface geology but more correlated to the low quality of the civil structures present in the area, including old buildings of the last century.

Description: Submitted

Description: 12-36

Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale

Description: JCR Journal

Description: open

Description: El Chichón volcano (Chiapas, Mexico) erupted violently in March–April 1982, breaching through the former volcano–hydrothermal system. Since then, the 1982 crater has hosted a shallow (1–3.3 m, acidic (pH ∼ 2.2) and warm (∼ 30 °C) crater lake with a strongly varying chemistry (Cl/SO4=0–79 molar ratio). The changes in crater lake chemistry and volume are not systematically related to the seasonal variation of rainfall, but rather to the activity of near-neutral geyser-like springs in the crater (Soap Pool). These Soap Pool springs are the only sources of Cl for the lake. Their geyser-like behaviour with a long-term (months to years) periodicity is due to a specific geometry of the shallow boiling aquifer beneath the lake, which is the remnant of the 1983 Cl-rich (24,000 mg/l) crater lake water. The Soap Pool springs decreased in Cl content over time. The zero-time extrapolation (1982, year of the eruption) approaches the Cl content in the initial crater lake,meanwhile the extrapolation towards the future indicates a zero-Cl content by 2009±1. This particular situation offers the opportunity to calculate mass balance and Cl budget to quantify the lake–spring system in the El Chichón crater. These calculations show that the water balance without the input of SP springs is negative, implying that the lake should disappear during the dry season. The isotopic composition of lake waters (δD and δ18O) coincide with this crater lake-SP dynamics, reflecting evaporation processes and mixing with SP geyser and meteoric water. Future dome growth, not observed yet in the post-1982 El Chichón crater, may be anticipated by changes in lake chemistry and dynamics.

Description: Published

Description: 237–248

Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: JCR Journal

Description: reserved

Description: El Chichón crater lake appeared immediately after the 1982 catastrophic eruption in a newly formed, 1-km wide, explosive crater. During the first 2 years after the eruption the lake transformed from hot and ultraacidic caused by dissolution of magmatic gases, to a warm and less acidic lake due to a rapid “magmatic-tohydrothermal transition” — input of hydrothermal fluids and oxidation of H2S to sulfate. Chemical composition of the lake water and other thermal fluids discharging in the crater, stable isotope composition (δD and δ18O) of lake water, gas condensates and thermal waters collected in 1995–2006 were used for the mass-balance calculations (Cl, SO4 and isotopic composition) of the thermal flux from the crater floor. The calculated fluxes of thermal fluid by different mass-balance approaches become of the same order of magnitude as those derived from the energy-budget model if values of 1.9 and 2 mmol/mol are taken for the catchment coefficient and the average H2S concentration in the hydrothermal vapors, respectively. The total heat power from the crater is estimated to be between 35 and 60 MW and the CO2 flux is not higher than 150 t/day or ~200 gm−2 day−1.

Description: Published

Description: 472-481

Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: JCR Journal

Description: reserved

Description: In June 2003, the geochemical composition of geothermal fluids was determined at 9 sites in the Vulcano hydrothermal system, including sediment seeps, geothermal wells, and submarine vents. Compositional data were combined with standard state reaction properties to determine the overall Gibbs free energy (deltaGr) for 120 potential lithotrophic and heterotrophic reactions. Lithotrophic reactions in the H-O-N-S-C-Fe system were considered, and exergonic reactions yielded up to 120 kJ per mole of electrons transferred. The potential for heterotrophy was characterized by energy yields from the complete oxidation of 6 carboxylic acids—formic, acetic, propanoic, lactic, pyruvic, and succinic—with the following redox pairs:O2/H2O, SO4 2-/H2S, NO3 -/NH4+, S0/H2S, and Fe3O4/Fe2+. Heterotrophic reactions yielded 6–111 kJ/mol e-. Energy yields from both lithotrophic and heterotrophic reactions were highly dependent on the terminal electron acceptor (TEA); reactions with O2 yielded the most energy, followed by those with NO3-, Fe(III), SO4 2-, and S0. When only reactions with complete TEA reduction were included, the exergonic lithotrophic reactions followed a similar electron tower. Spatial variability in deltaGr was significant for iron redox reactions, owing largely to the wide range in Fe2+ and H+ concentrations. Energy yields were compared to those obtained for samples collected in June 2001. The temporal variations in geochemical composition and energy yields observed in the Vulcano hydrothermal system between 2001 and 2003 were moderate. The largest differences in deltaGr over the 2 years were from iron redox reactions, due to temporal changes in the Fe2+ and H+ concentrations. The observed variations in fluid composition across the Vulcano hydrothermal system have the potential to influence not only microbial diversity but also the metabolic strategies of the resident microbial communities.

Description: Published

Description: 905-932

Description: 4.5. Degassamento naturale

Description: JCR Journal

Description: reserved

Description: We designed a new seismic source model for Italy to be used as an input for country-wide probabilistic seismic hazard assessment (PSHA) in the frame of the compilation of a new national reference map. We started off by reviewing existing models available for Italy and for other European countries, then discussed the main open issues in the current practice of seismogenic zoning. The new model, termed ZS9, is largely based on data collected in the past 10 years, including historical earthquakes and instrumental seismicity, active faults and their seismogenic potential, and seismotectonic evidence from recent earthquakes. This information allowed us to propose new interpretations for poorly understood areas where the new data are in conflict with assumptions made in designing the previous and widely used model ZS4. ZS9 is made out of 36 zones where earthquakes with Mw 〉= 5 are expected. It also assumes that earthquakes with Mw up to 5 may occur anywhere outside the seismogenic zones, although the associated probability is rather low. Special care was taken to ensure that each zone sampled a large enough number of earthquakes so that we could compute reliable earthquake production rates. Although it was drawn following criteria that are standard practice in PSHA, ZS9 is also innovative in that every zone is characterised also by its mean seismogenic depth (the depth of the crustal volume that will presumably release future earthquakes) and predominant focal mechanism (their most likely rupture mechanism). These properties were determined using instrumental data, and only in a limited number of cases we resorted to geologic constraints and expert judgment to cope with lack of data or conflicting indications. These attributes allow ZS9 to be used with more accurate regionalized depth-dependent attenuation relations, and are ultimately expected to increase significantly the reliability of seismic hazard estimates.

Description: Published

Description: 85-108

Description: 3.2. Tettonica attiva

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: JCR Journal

Description: reserved

Description: An evaluation of the actual reliability of probabilistic seismic hazard (PSH) assessments, provided by existing numerical techniques, is mandatory to orientate new researches and improvements. Two procedures devoted to this task are proposed, which are based on the comparison of the hazard estimates with empirical observations (e.g. strong-motion data). These procedures have been applied to the estimates provided by the methodology adopted for most recent seismic hazard evaluations in Italy. The analysis shows that a significant mismatch exists between peak ground acceleration values characterized by an exceedence probability of 10 per cent in 30 yr and what has actually been observed at 68 accelerometric stations located on stiff soil, where continuous seismicity monitoring has been performed in the last 30 yr. Although this finding should be considered with caution, it suggests that a future re-examination of the adopted PSH computational model could be useful to avoid possible underestimates of seismic hazard in Italy.

Description: Published

Description: 1088–1094

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: JCR Journal

Description: reserved

Description: Viene descritto il percorso metodologico adottato per gli studi di microzonazione sismica nella provincia di Campobasso, colpita dal terremoto del 2002. Questi studi hanno permesso una completa ed omogenea caratterizzazione della geologia, della geomorfologia e delle caratteristiche geotecniche dei terreni di tutti i centri urbani esistenti. Per valutare le azioni sismiche di progetto, da utilizzare nella successiva fase della ricostruzione, sono stati calcolati i fattori di amplificazione sismica locale per aree omogenee del centro abitato. Il prodotto finale dell'attività è stata la redazione delle mappe di microzonazione sismica dei centri abitati.

Description: Published

Description: 293

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: reserved

Description: Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the pathways and the mechanisms of Hg cycling through the Earth's geochemical reservoirs and to assess its environmental impacts. While previous studies have suggested that degassing volcanoes might contribute importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm]. Positive co-variations of (THg) with sulphate indicate that Hg-SO4-rich acid groundwaters receive a direct input of magmatic/hydrothermal gases carrying mercury as Hg0 (gas). Increasing THg in a volcanic aquifer could thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different aqueous forms of this element in our samples.We find that dissolved elemental Hg0 (aq) and particulate-bound Hg (HgP) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto colloidal particles. Moreover, we observe that dissolved Hg0 aq and Hg(II) forms coexist in comparable amount in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore, chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we provide a first quantitative comparison of the relative intensity of aqueous transport and atmospheric emissions of mercury at Mount Etna, a very active basaltic volcano.

Description: Published

Description: 96-106

Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi

Description: JCR Journal

Description: reserved

Description: The fundamental goal of this chapter is to provide a summary of the seismotectonics of the Messina Strait with special reference to the 28th December 1908 earthquake, the bridge Design Earthquake. We summarize what is known about the earthquake, describe the source model that has been used for assessing the bridge design seismic action (see Section 5.2. Seismic hazard and design earthquakes) and discuss some short- and long- term implications of tectonic activity in the area.

Description: Published

Description: 2-17

Description: 4.1. Metodologie sismologiche per l'ingegneria sismica

Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale

Description: reserved

Description: More than 100 3 ~ e / 4i~soeto pe ratios were measured in CO,-dominated gas samples collected during the 1997-1 998 seismic crisis that shook the Umbria-Marche, Central Apennines, Italy. Although the gas emissions were located in a typical "crustal" environment the measured values delineate variable mixing proportions between mantle-derived and crustal helium. During the monitoring period anomalous 3 ~ e P r~atieos were observed, together with a significant increase of fluid outflows. The observed 3 ~ e Pa~noema lies appear to be driven by stress-induced crustal deformations affecting micro-fracturing and bulk permeability and, in turn, by a seismogenic-induced modification of the crustal permeability of rocks. Since crustal deformations can also occur aseismically, the geochemical anomalies must be considered indicators of processes occurring below the surface, which could eventually help to estimate the probability increase of an impending earthquake, instead of pure empirical precursors.

Description: Published

Description: 839-842

Description: 3.2. Tettonica attiva

Description: JCR Journal

Description: reserved

Description: A raingauge network made of six stations was installed in the Hyblean region. Stations were located at different altitudes (from 5 m to 986 m a.s.l.) and along two directions (E-W and SW-NE). Rainwater samples were monthly collected for stable isotope measurements. Spatial distribution of rainwater isotope composition has confirmed the wet air masses move from South-East/South-West toward North. Water balance has highlighted that the annual volume of infiltrating waters is in the range of 1-1.5 *105 m3 Km-2. 82 well waters and 12 spring waters located within the Hyblean Plateau (South-Estern Sicily), were also collected from 1999 to 2001 during several surveys for chemical (major,minor and trace elements) analyses. Water chemistry allowed to identify two main aquifers: the first aquifer hosted within sedimentary rocks is characterized by earthalkaline bicarbonate waters, while the second aquifer, located within the volcanic deposits (mainly towards North- North-East) is characterized by groundwaters evolving from earthalkaline bicarbonate water-type towards a Na-HCO3-type. A slightly anomaly in water temperature (24-28°C) have been identified along the northern margin, while the lower Eh values have been recorded along the M.Lauro-Scicli and the Hyblean Malta Escarpment fault systems. Isotope composition of groundwaters has suggested the occurrence of evaporative processes during soil infiltration having a dD/d18O slope close to 4.5. Chemical and isotope composition of dissolved gases (d13CTDIC, d13CCH4, 3He/4He) have revealed, as expected, that deeply-derived gases rise along the main tectonic discontinuities. Chemical and isotope analyses of dissolved carbon have revealed the existence of two sampling sites (NA and FE samples) attesting the interaction between groundwaters and a consistent amount of deep inorganic carbon dioxide. He isotope ratios (from 0.81Ra to 6.19 Ra) have revealed the occurrence of mixing process, in different proportions, between crustal and mantle components. On the base of the obtained results, a clear picture of the groundwaters circulation within the Hyblean aquifers has been drawn. In framework of projecting of a geochemical network for the continuous monitoring of the local seismic activity the most suitable geochemical parameters and the sites of great interest have been identified.

Description: - Unione Europea Fondo Sociale Europeo; - Ministero dell’Università e della Ricerca Scientifica e Tecnologica; - Università degli studi di Palermo

Description: Published

Description: open

Description: A new method for extracting dissolved gases in natural waters has been developed and tested, both in the laboratory and in the field. The sampling device consists of a polytetrafluroethylene (PTFE) tube (waterproof and gas permeable) sealed at one end and connected to a glass sample holder at the other end. The device is pre-evacuated and subsequently dipped in water, where the dissolved gases permeate through the PTFE tube until the pressure inside the system reaches equilibrium. A theoretical model describing the time variation in partial gas pressure inside a sampling device has been elaborated, combining the mass balance and ‘‘Solution-Diffusion Model’’ which describes the gas permeation process through a PTFE membrane). This theoretical model was used to predict the temporal evolution of the partial pressure of each gas species in the sampling device. The model was validated by numerous laboratory tests. The method was applied to the groundwater of Vulcano Island (southern Italy). The results suggest that the new sampling device could easily extract the dissolved gases from water in order to determine their chemical and isotopic composition.

Description: - European Social Fund.

Description: Published

Description: Q09005

Description: partially_open

Description: The northwestern flank of the Colli Albani, a Quaternary volcanic complex near Rome, is characterised by high CO2 values and Rn activities in the groundwater and by the presence of zones with strong emission of gas from the soil. The most significant of these zones is Cava dei Selci where many houses are located very near to the gas emission site. The emitted gas consists mainly of CO2 (up to 98 vol) with an appreciable content of H2S (0.8). The He and C isotopic composition indicates, as for all fluids associated with the Quaternary Roman and Tuscany volcanic provinces, the presence of an upper mantle component contaminated by crustal fluids associated with subducted sediments and carbonates. An advective CO2 flux of 37 tons/day has been estimated from the gas bubbles rising to the surface in a small drainage ditch and through a stagnant water pool, present in the rainy season in a topographically low central part of the area. A CO2 soil flux survey with an accumulation chamber, carried out in February-March 2000 over a 12 000 m2 surface with 242 measurement points, gave a total (mostly conductive) flux of 61 tons/day. CO2 soil flux values vary by four orders of magnitude over a 160-m distance and by one order of magnitude over several metres. A fixed network of 114 points over 6350 m2 has been installed in order to investigate temporal flux variations. Six surveys carried out from May 2000 to June 2001 have shown large variations of the total CO2 soil flux (8/25 tons/day). The strong emission of CO2 and H2S, which are gases denser than air, produces dangerous accumulations in low areas which have caused a series of lethal accidents to animals and one to a man. The gas hazard near the houses has been assessed by continuously monitoring the CO2 and H2S concentration in the air at 75 cm from the ground by means of two automatic stations. Certain environmental parameters (wind direction and speed; atm P, T, humidity and rainfall) were also continuously recorded. At both stations, H2S and CO2 exceeded by several times the recommended concentration thresholds. The highest CO2 and H2S values were recorded always with wind speeds less than 1.5 m/s, mostly in the night hours. Our results indicate that there is a severe gas hazard for people living near the gas emission site of Cava dei Selci, and appropriate precautionary and prevention measures have been recommended both to residents and local authorities.

Description: - GNV funded research project Gas Hazard of Colli Albani

Description: Published

Description: 81^94

Description: partially_open

Description: Seismogenic stress orientations are estimated in the lithosphere of Sicily by inversion of 131 local earthquake focal mechanisms (FMs) selected from the literature. An average misfit F = 14.5° between stress tensor and FMs indicates that the entire set of earthquakes is generated by a highly heterogeneous stress field. Detailed analysis of stress tensors and related earthquake misfits obtained for tens of subsets based on spatial separation of data allowed us to identify two main stress domains in the study region: (i) a compressional domain, including Etna, western Sicily and the southern Tyrrhenian sea offshore Sicily, where the σ1 orientation roughly changes from NW–SE in the Etna area and western Sicily to NNE–SSW at the northeastern edge of the domain (Eolian Islands) and (ii) an extensional domain in northeastern Sicily between the Eolian Islands and Etna, where σ3 is oriented analogously to previously estimated in the easterly confining extensional area of the Messina Straits. General agreement is found between this stress pattern and the GPS crustal displacement vectors reported in the most recent literature for the study region. Moreover, stress inversion enables us to locate the extensional domain more accurately than the presently available GPS data. Finally, the stress orientations estimated in the southern and western sectors of the study area (Etna and western Sicily on and offshore) match well with the displacement fields predicted for Sicily by large-scale models of plate motion, conversely a mismatch is observed in the northeastern sector (Eolian Islands and northeastern Sicily). We suggest that the joint action of Africa–Eurasia convergence and Ionian subduction trench retreat (rollback of the subducting slab) may explain the stress pattern detected in Sicily in the present study. Work for computation of a finite-element regional geodynamic model based on geophysical and geological data collected over the last few years has recently started with the purpose of quantitatively checking this hypothesis.

Description: Published

Description: partially_open

Description: An anisotropic attenuation law, based on an anisotropic characterization of intensity distribution for seismogenic zones, is proposed. This approach, that distinguishes itself for its consistency to the observed data, initially reconfigured by filtering procedures, is particularly suitable for seismic hazard evaluation.

Description: Published

Description: 707-714

Description: partially_open

Description: Despite its impact in understanding oceanic crust formation and eruptive styles of related volcanism, magma dynamics at midocean ridges are poorly known. Here, we propose a new method to assess ascent rates of mid-ocean ridge basalt (MORB) magmas,as well as their pre- and sin-eruptive dynamics. It is based on the idea that a rising magma can reach a variable degree of both CO2 supersaturation in melt and kinetic fractionation among noble gases in vesicles in relation to its ascent rate through the crust. To quantify the relationship, we have used a model of multicomponent bubble growth in MORB melts, developed by extending the single-component model of Proussevitch and Sahagian [A.A. Proussevitch, D.L. Sahagian, Dynamics and energetics of bubble growth in magmas: analytical formulation and numerical modeling, J. Geophys. Res. 103 (1998), 18223–18251.] to CO2–He–Ar gas mixtures. After proper parameterization, we have applied it to published suites of data having the required features (glasses from Pito Seamount and mid-Atlantic ridges). Our results highlight that the investigated MORB magmas display very different ranges of ascent rates: slow rises of popping rock forming-magmas that cross the crust (0.01–0.5 m/s), slightly faster rates of energetic effusions (0.1–1 m/s), up to rates of 1–10 m/s which fall on the edge between lava effusion and Hawaiian activity. Inside a single plumbing system, very dissimilar magma dynamics highlight the large differences in compressive stress of the oceanic crust on a small scale. Constraints on how the systems of ridges work, as well as the characteristics of the magmatic source, can also be obtained. Our model shows how measurements of both the dissolved gas concentration in melt and the volatile composition of vesicles in the same sample are crucial in recognizing the kinetic effects and definitively assessing magma dynamics. An effort should be made to correctly set the studied samples in the sequence of volcanic submarine deposits where they are collected. Enhanced knowledge of a number of physical properties of gas-bearing MOR magmas is also required, mainly noble gas diffusivities, to describe multicomponent bubble growth at a higher confidence level.

Description: Published

Description: 138-158

Description: partially_open

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

Description: open

Description: A digitization has been performed of all volcanic rock fragments, main thrust fronts and fold axes from the 'Synthetic Structural Kinematic Map' as well as of all intrasedimentary magnetic bodies from the map of Cassano et al. These two maps complement each other, and the buried magnetized bodies fill the gaps of volcanic rocks in various regions e.g. in Tuscany. Some other major gaps can be found along the Northern Apennines, the Central and Southern Apennines and the Calabrian arc. A comparison of a map representing the 'Log C - seismic macrozonation index' to the pattern of all volcanic rocks, reveals that more seismic energy is released in those areas where volcanic rocks are absent or where their continuity in space is interrupted. Furthermore seismic activity is inhibited in those areas where minimum values of Bouguer anomalies are recorded.

Description: Published

Description: 165-181

Description: reserved

Description: - Many people in this room are geologists (in a broad sense!) - Most of them are (directly or indirectly) involved in Seismic Hazard Assessment at national or local level - Geologists are indeed forcing a revolution in SHA practice. Let’s keep up the good work! - I will be supplying some “food for thought” for an ever-growing community that sometimes needs to look back and recalibrate its efforts - They are here because their work relates somehow to Earthquake Geology

Description: Unpublished

Description: Vienna, Austria, 02-07 april 2006

Description: open

Description: Several types of natural gas emissions (soil gas, low temperature fumaroles, gas bubbling in mud pools) were collected monthly on Mt. Etna volcano between July 2000 and July 2003 both from its summit and its flanks. Samples were analysed for the determination of the concentrations of CO2, CH4, He, H2, CO as well as the isotopic ratios of 13 14 C/ C of CO2 (δ13C) and He (R/Ra). The analysed gases were chemically divided into two groups: air-contaminated (from sites closer to the summit vents of Mt. Etna) and CO2 - rich. Among the latter, samples from the lower SW flank of the volcano showed high contents of biogenic thermogenic and/or microbial CH4. Isotopic shift in the δ13C values is caused by input of organic CO2 and/or by interaction between magmatic CO2 and shallow ground water as a function of water temperature and CO2 flux from depth. Based on a graphic method applied to δ13 TDIC C of some ground water, the inferred isotopic composition of the pristine magmatic gas at Mt. Etna is characterised by δ13C values ranging from -2 to -1 0 00 . During the period July 2000 - July 2003 significant variations were observed in many of the investigated parameters almost at all monitored sites. Seasonal influences were generally found to be negligible, with only a limited effect of air temperature changes on soil CO2 and ground temperature in only two of the air-contaminated sites. The largest chemical anomalies were observed in the air-contaminated sites, probably because of the strong buffering power of local ground water on gases released through the most peripheral areas where the CO2-rich sites are located. The anomalous changes observed during the study period can be explained in terms of progressive gas release from separate batches of magma that ascend towards the surface in a step-wise manner. Data relevant to the period following the 2002-03 eruption suggest that magma kept accumulating beneath the volcano, thus increasing the probability of a new large eruption at Mt. Etna.

Description: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo

Description: Published

Description: 805-841

Description: open

Description: Gas seepages along the Ionian coast of the northwestern Peloponnesus (Greece), at Killini, Katakolo, and Kaiafas reflect deep hydrocarbon-generation processes and represent a real hazard for humans and buildings. Methane microseepage, gas concentration in offshore and onshore vents, and gas dissolved in water springs, including the isotopic analysis of methane, have shown that the seeps are caused by thermogenic methane that had accumulated in Mesozoic limestone and had migrated upward through faults, or zones of weakness, induced by salt diapirism. A link between local seismicity and salt tectonics is suggested by the analyses of hypocenter distribution. Methane acts as a carrier gas for hydrogen sulfide produced by thermal sulfate reduction and/or thermal decomposition of sulfur compounds in kerogen or oil. Methane seeps in potentially explosive amounts, and hydrogen sulfide is over the levels necessary to induce toxicological diseases and lethal effects.

Description: Published

Description: 701-713

Description: reserved

Description: Short commentary sent to the APRE commission for the Latin American - Europe scientific cooperation

Description: Analysis of a relocated hypocentres database and of a global volcanic eruptions catalogue has made clear that the South American Pacific margin is a site of peculiar phenomena and related geophysical events. The already known maximum rate of deep earthquakes, the expected mean recurrence time of extreme magnitude earthquakes of a few tens of years, and the closeness of the region to the Nazca triple point – i.e. the region with the maximum rate of sea floor expansion – mean that the Andean margin deserves priority in preparing stable geophysical instrument arrays in anticipation of the next great earthquake, with the aim of increasing our understanding of the real nature of earthquakes, of the real geodynamics of active margins, and of global geodynamics and tectonics

Description: Published

Description: 60-68

Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive

Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive

Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani

Description: 3.1. Fisica dei terremoti

Description: 3.2. Tettonica attiva

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: 3.6. Fisica del vulcanismo

Description: 4.3. TTC - Scenari di pericolosità vulcanica

Description: 5.2. TTC - Banche dati di sismologia strumentale

Description: 5.6. Consulenze nell'ambito di trattati internazionali

Description: N/A or not JCR

Description: open

Description: A new method using ammonia solutions in pre-evacuated quartz bottles has been experimented for volcanic gas sampling and analysing. Various tests (reproducibility, variability and comparison with known methods such as NaOH pre-evacuated bottles and acid condensates) have been performed to check for their efficiency. By using ammonia solutions, acid gases (St, HCl, HF), carbon dioxide, noncondensible gases (N2, Ar, …) and metallic trace elements (MTE) can be measured with standard methods (HPLC, GC, titrimetry, ICP-MS). Results showthat acid gases, CO2 and noncondensible gases are sampled and analysedwith similar efficiency inNH4OHbottles than by using the known and accurate NaOH method.Moreover, a key point is that NH4OH solutions, after undergoing adequate processing (oxidation and acidification) allow also precise MTE measurements by using standard ICP-MS methods. Such MTE measurements appear much more reliable than those performed on acid condensates. Pre-evacuated ammonia bottles appear therefore as an optimum tool to collect volcanic gases and to obtain their complete chemical composition.

Description: Published

Description: 244-256

Description: JCR Journal

Description: reserved

Description: This paper presents the results of different numerical analyses (nonlinear dynamic FEM simulations) regarding the monumental buildings in Ripabottoni village (Campobasso, southern Italy), which were damaged by the 2002 Molise earthquake. In particular, the church of S. Maria Assunta, for which typological data and an exhaustive damage survey are available, is taken into account. Some preliminary studies [Spallarossa et al., 2004], which correlate the waveform of the available recordings from aftershocks and the surveyed damage mechanism (due to the crushing of the vertical structural elements), suggested that a feasible explanation for this particular damage pattern does not involve only the intrinsic vulnerability of this type of buildings, but deals also with the high energy content in the high frequency range observed in the vertical component of the seismic events. In order to understand the structural damage patterns surveyed, synthetic accelerograms, representative of the main shock (Ml = 5.4 on 31 October 2002), were computed. The Empirical Green Function (EGF) method was applied to compute the seismic input adopted in the nonlinear dynamic analyses that we performed for the church of S. Maria Assunta. The results confirm that the observed damage pattern cannot totally be put down to the vulnerability of the building, but the particular characteristics of the seismic action played a fundamental role in determining it.

Description: Published

Description: 381-409

Description: reserved

Description: Volcanic areas release huge amounts of gases, which apart from having important influences on the global climate could have strong impact on human health. Gases have both acute and chronic effects. Carbon Dioxide and Sulphur gases are the main gases responsible for acute mortality due to their asphyxiating and/or toxic properties. On the contrary Mercury and Radon have important chronic effects respectively for its toxicity and radioactivity. The problem has long been neglected until the “Lake Nyos” catastrophe in 1986, in which about 1700 people were killed by a volcanic CO2 emission, attracted the worldwide attention of the mass media. In this paper we present some studies on gas hazard in three different volcanic systems chosen for their different activity status: Mt. Etna (Italy), characterised by frequent activity with a mean CO2 emission of about 450 kg s-1; Pantelleria island (Italy) at present in quiescent status and a CO2 emission of about 12 kg s-1; and Sousaki (Greece) a recent (Quaternary) but now extinct volcano with a CO2 emission of about 0.6 kg s-1. In all three systems the main problems arise from CO2 emissions while secondary problems are due to SO2 and Hg (Etna), H2S (Sousaki) and Rn (Pantelleria).

Description: Published

Description: 369-378

Description: open

Description: The sustained and uninterrupted plume degassing at Mount Etna volcano, Southern Italy, represents the troposphere’s most prominent natural source of fluorine. Of the ~ 200 Mg of fluorine (as HFg) emitted daily by the volcano, 1.6±2.7 Mg are deposited by wet and dry deposition. Fluorine-deposition via volcanic ash, here characterised for the first time, can be quite significant during volcanic eruptions (i.e. 60 Mg of fluorine were deposited during the 2001 eruption through volcanic ash, corresponding to ~ 85% of the total fluorine deposition). Despite the fact that these depositions are huge, the fate of the deposited fluorine and its impact on the environment are poorly understood. We herein present original data on fluorine abundance in vegetation (Castanea Sativa and Pinus Nigra) and andosoils from the volcano’s flank, in the attempt to reveal the potential impact of volcanogenic fluorine emissions. Fluorine contents in chestnut leaves and pine needles are in the range 1.8-35 µg/g and 2.1-74 µg/g respectively; they exceed the typical background concentrations in plants growing in rural areas, but fall within the lower range of typical concentrations in plants growing near high fluorine anthropogenic emission sources. The rare plume fumigations on the lower flanks of Mt Etna (distance 〉 4 km from summit craters) are probably the cause of the “undisturbed” nature of Etnean vegetation: climatic conditions, which limit the growth of vegetation on the upper regione deserta, are a natural limit to the development of more severe impacts. High fluorine contents, associated with visible symptoms, were only measured in pine needles at three sites, located near recently-active (2001 to 2003) lateral eruptive fractures. Total fluorine contents (FTOT) in the Etnean soils have a range of 112-341 µg/g, and fall within the typical range of undisturbed soils; fluorine extracted with distilled water (FH2O) have a range of 5.1 to 61 µg/g and accounts for 2-40 % of FTOT. FH2O is higher in topsoils from the eastern flank (downwind), while it decreases with depth in soil profiles and on increasing soil grain size (thereby testifying to its association with clay-mineral-rich, fine soil fractions). The fluorine adsorption capacity of the andosoils acts as a natural barrier that protects the groundwater system.

Description: Published

Description: 87-101

Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Description: 4.5. Degassamento naturale

Description: JCR Journal

Description: reserved

Description: Introduction of a special issue of the journal

Description: no abstract

Description: Published

Description: 1-4

Description: 4.5. Degassamento naturale

Description: JCR Journal

Description: reserved

Description: The Jalisco block is a geologically and tectonically complex part of western Mexico. It is considered a distinct crustal unit bounded toward the mainland by rifting and toward the Pacific ocean by the SW section of the Mid-America trench, a contact between the subducting Rivera plate and the continent. On the basis of chemical, helium, and carbon isotopic analyses of 37 groups of thermal springs widely distributed over the Jalisco block, several major tectonic environments can be distinguished. The highest R= 3He/4He ratios with R/Ra (Ra being the atmospheric 3He/4He ratio) approaching MORB values were observed along the Trans-Mexican Volcanic Belt (TMVB) and within the Colima volcanic complex. For springs in the inner part of the block and close to the Pacific coast, including submarine springs at Punta de Mita, typical values were much lower, with R/Ra down to 0.4. A negative correlation between 3He/4He and δ13C of CO2 is suggested to be the result of coupling between radiogenic He and CO2 formed by oxidation of organic-rich sediments. C/3He ratios vary from ~109 for TMVB, typical for volatiles released from the mantle, to 〉 1011 thus suggesting a substantial addition of carbon from the crust.

Description: Published

Description: 459-466

Description: open

Description: In this article the implementation and potential of the Seismotectonic Information System of the Campania Region (SISCam) are described, in particular an application of this Web-based GIS system to the seismotectonic analysis of the Sannio area (Southern Apennines) is performed. WEB-GIS technologies greatly contribute to both the environmental monitoring and the disaster management of areas affected by high natural risks. Specifically the SISCam system has been developed with the aim of providing easy access and fast diffusion, through Internet technology, of the most significant geological, geophysical, and territorial data relative to the Campania Region. The Sannio area has been selected as our application example because it is among the most active seismic regions in Italy. This portion of the Southern Apennines which was hit by the June 5, 1688 strong earthquake (MW = 6.7, CPTI 1999) and by some low- and moderate-energy seismic sequences (1990–1992, 1997), is characterized by a complex inherited tectonic setting and low-tectonic deformation rates that hide the seismogenic sources position. Since this case study turned out to be complicated, the use of the SIScam WEB-GIS has become indispensable because it allowed us to visualize, integrate and analyze all the data available, in order to obtain an accurate and direct picture of the seismotectonic setting of the area. Moreover, a different approach of data analysis was necessary, due to the lack of up-todate neotectonic and structural data; therefore, the operation of this GIS system enabled us to process and generate some original informative layers, through image analysis, such as new structural lineaments represented on a map of the potential active faults of the area, which has been the final result of our application, as a contribution to new knowledge about the local seismic risk parameters.

Description: Published

Description: on line first

Description: 5.4. TTC - Sistema Informativo Territoriale

Description: JCR Journal

Description: reserved

Description: Manifestations of recent volcanism in the Greater Caucasus are grouped in the El’brus and Kazbek volcanic areas [1]. The last episodes of activity in the majority of their eruptive centers date back to the Late Holocene or even first centuries of the recent era (El’brus Volcano) [2]. This implies potential volcanic hazards in the Greater Caucasus. Therefore, it is important to outline contours of this potentially hazardous region with the maximal possible accuracy. The region is characterized by indications of geodynamic stress, such as recent eruptions, crustal deformations, seismic activity, geothermal anomalies, and others. The3He/4He value in natural gases can serve as one of such indications.

Description: Published

Description: 239–242

Description: 3.2. Tettonica attiva

Description: JCR Journal

Description: reserved

Description: The influx of fluids into fault zones can trigger two main types of weakening processes that operate over different timescales and facilitate fault movement and earthquake nucleation. Short-term and long-term weakening mechanisms along faults require a continuous fluid supply near the base of the brittle crust, a condition satisfied in the extended/extending area of the Northern Apennines of Italy. Here carbon mass balance calculations, coupling aquifer geochemistry to isotopic and hydrological data, define the presence of a large flux (∼12,160 t d-1) of deep-seated CO2 centred in the extended sector of the area. In the currently active extending area, CO2 fluid overpressures at ∼85% of the lithostatic load have been documented in two deep (4-5 km) boreholes. In the long-term, field studies on an exhumed regional low-angle normal fault show that during the entire fault history, fluids reacted with fine-grained cataclasites in the fault core to produce aggregates of weak, phyllosilicate-rich fault rocks that deform by fluid assisted frictional-viscous creep at sub-Byerlee friction values (μ 〈 0.3). In the short-term, fluids can be stored in structural traps, such as beneath mature faults, and stratigraphical traps such as Triassic evaporites. Both examples preserve evidence for multiple episodes of hydrofracturing induced by short-term cycles of fluid pressure build-up and release. Geochemical data on the regional-scale CO2 degassing process can therefore be related to field observations on fluid rock interactions to provide new insights into the deformation processes responsible for active seismicity in the Northern Apennines.

Description: Submitted

Description: 4.5. Degassamento naturale

Description: N/A or not JCR

Description: open

Description: Istituto Nazionale di Geofisica e Vulcanologia Dipartimento della Protezione Civile

Description: Unpublished

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open

Description: On the night between 14 and 15 January of 1466, an earthquake damaged towns close to those recently destroyed by the 1980 Irpinia earthquake. It was felt in Naples, about 80 km from the epicentre, resulting in panic and slight damage. To obtain source parameters related to January 15, 1466, the observed macroseismic field of the November 23, 1980 earthquake was reproduced by synthetic peak strong acceleration. The results suggest that the whole of the 1466 faulting was also activated by the 1980 event, and that the northern part remained non-activated. Quite possibly, the near southernmost source of a large earthquake in 1456 affected the occurrence of the event nearby ten years later. Furthermore, the value of Mo=7.5 1018 Nm obtained allows the medieval event in 1466 to number among the most severe recorded in southern Italy.

Description: Published

Description: 115-126

Description: 3.1. Fisica dei terremoti

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: 3.10. Sismologia storica e archeosismologia

Description: 5.1. TTC - Banche dati e metodi macrosismici

Description: N/A or not JCR

Description: reserved

Description: Metamorphic and magmatic garnets are known to fractionate REE, with generally HREE-enriched patterns, and high Lu/ Hf and Sm/Nd ratios, making them very useful as geochemical tracers and in geochronological studies. However, these garnets are typically Al-rich (pyrope, almandine, spessartine, and grossular) and little is known about garnets with a more andraditic (Fe3+) composition, as frequently found in skarn systems. This paper presents LA-ICP-MS data for garnets from the Crown Jewel Au-skarn deposit (USA), discusses the factors controlling incorporation of REE into garnets, and strengthens the potential of garnet REE geochemistry as a tool to help understand the evolution of metasomatic fluids. Garnets from the Crown Jewel deposit range from Adr30Grs70 to almost pure andradite (Adr〉99). Fe-rich garnets (Adr〉90) are isotropic, whereas Al-rich garnets deviate from cubic symmetry and are anisotropic, often showing sectorial dodecahedral twinning. All garnets are extremely LILE-depleted, Ta, Hf, and Th and reveal a positive correlation of RREE3+ with Al content. The Al-rich garnets are relatively enriched in Y, Zr, and Sc and show ‘‘typical’’ HREE-enriched and LREE-depleted patterns with small Eu anomalies. Fe-rich garnets (Adr〉90) have much lower RREE and exhibit LREE-enriched and HREE-depleted patterns, with a strong positive Eu anomaly. Incorporation of REE into garnet is in part controlled by its crystal chemistry, with REE3+ following a coupled, YAG-type substitution mechanism ð½ X2þ VIII 1 ½REE3þ VIII þ1 ½ Si4þ IV 1½Z3þ IV þ1Þ, whereas Eu2+ substitutes for X2+ cations. Thermodynamic data (e.g., Hmixing) in grossular– andradite mixtures suggest preferential incorporation of HREE in grossular and LREE in more andraditic compositions. Variations in textural and optical features and in garnet geochemistry are largely controlled by external factors, such as fluid composition, W/R ratios, mineral growth kinetics, and metasomatism dynamics, suggesting an overall system that shifts dynamically between internally and externally buffered fluid chemistry driven by fracturing. Al-rich garnets formed by diffusive metasomatism, at low W/R ratios, from host-rock buffered metasomatic fluids. Fe-rich garnets grow rapidly by advective metasomatism, at higher W/R ratios, from magmatic-derived fluids, consistent with an increase in porosity by fracturing.

Description: Published

Description: 185-205

Description: 3.6. Fisica del vulcanismo

Description: 3.8. Geofisica per l'ambiente

Description: JCR Journal

Description: reserved

Description: Data for major, minor and trace elements in groundwaters from Mt. Etna volcano collected in 1994, 1995 and 1997 were analysed using Cluster Analysis (CA). Two groups of sampling sites were identified (named clusters A and B), mainly on the basis of their different salinity and content of dissolved CO2. The highest levels of both of these parameters were observed in the sites of cluster A, located in the lower south-western and central eastern flanks of the volcano. For both of the statistical groups, CA was repeated taking into account the mean values of each parameter in time, and the results allowed us to recognize four distinct groups of parameters for each group of sites on the basis of their temporal patterns. Four different types of temporal patterns were recognised: concave, convex, increasing, decreasing. The observed changes were basically interpreted as a result of the different response of dissolved chemical elements to changes in the aqueous environment and/or in their solubility/mobility in water due to different rates of input of magmatic gases to Etna’s aquifers. The main changes occurred in 1995, when Etna’s volcanic activity resumed after a two-year period of rest. The temporal changes of the majority of the studied parameters (water temperature, water conductivity, Eh, pH, Al, Mg, B, Ca, Cl-, Hg, Mn, Mo, Na, Ni, Se, Si, Sr, Cr Zn and pCO2) were not cluster-dependent, therefore they were not apparently affected by differences in water salinity between the two groups of sampling sites. A limited number of parameters (Ti, K, Li, HCO3-, As, Fe, SO42-, Cu and V), however, showed different behaviours depending on the cluster of sites which they belonged to, thus suggesting their apparent dependency on water salinity.

Description: Unpublished

Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Description: JCR Journal

Description: open

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

Description: 4.2. TTC - Scenari e mappe di pericolosità sismica

Description: open