ALBERT

Description: The CROP-11 deep seismic profile across the central Apennines, Italy, reveals a previously unknown, mid-crustal antiform here interpreted as a fault-bend fold-like structure. The seismic facies and gravity signature suggest that this structure consists of low-grade metamorphic rocks. Geomorphological, stratigraphic and tectonic evidence in the overlying shallow thrusts suggests that this structure developed in early to mid-Messinian time and grew out of sequence in late Messinian– Pliocene time. The out-of-sequence growth may reflect a taper subcriticality stage of the Apenninic thrust wedge, which induced renewed contraction in the rear.

Description: Published

Description: 583–586

Description: open

Description: During the July^August 2001 eruption of Mt. Etna development of extensional fractures/faults and grabens accompanied magma intrusion and subsequent volcanic activity. During the first days of the eruption, we performed an analysis of attitude, displacement and propagation of fractures and faults exposed on the ground surface in two sites, Torre del Filosofo and Valle del Leone, located along the same fracture system in the region surrounding the Valle del Bove depression on the eastern flank of Mt. Etna. Fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system. The investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes. In particular, the fracture system propagated parallel to the gentle slope (67‡ dip) in the Torre del Filosofo area, and perpendicular to the steep slope (V25‡ dip) in the Valle del Leone area. In the Torre del Filosofo area, slight graben subsidence and horizontal extension of the ground surface by about 3 m were recorded. In the Valle del Leone area, extensional faulting forming a larger and deeper graben with horizontal extension of the ground surface by about 10 m was recorded. For the Valle del Leone area, we assessed a downhill dip of 14‡ for the graben master fault at the structural level beneath the graben where the fault dip shallows. These results suggest that dyke intrusion at Mount Etna, and particularly in the region surrounding the Valle del Bove depression, may be at the origin of slope failure and subsequent slumps where boundary conditions, i.e. geometry of dyke, slope dip and initial shear stress, amongst others, favour incipient failures.

Description: Published

Description: 281-294

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

Description: 3.2. Tettonica attiva

Description: 3.5. Geologia e storia dei sistemi vulcanici

Description: 3.6. Fisica del vulcanismo

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: Two major deformation belts occur in the portion of the Adriatic Sea offshore the Gargano Promontory. The NE-SW - trending Tremiti Deformation Belt, located north of the Gargano Promontory, originated during the Plio- Quaternary, while the E-W-trending South Gargano Deformation Belt, located south of the Gargano Promontory, formed in a time span from Eocene to Early Pliocene. These deformation belts may have originated by tectonic inversion of Mesozoic extensional faults. This inversion tectonics, of Tertiary age, can be related to the evolution of the fold-and thrust belts surrounding the Adriatic Sea. The whole of the study area is, at present, seismically active and represents a preferential site of deformation.

Description: Published

Description: 573-578

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: The eruptive events of the July–August 2001 and October 2002–January 2003 at Mt. Etna provide new insights for reconstructing the complex geometry of the feeding system and their relationship to regional tectonics. The 2001 eruption took place mainly on the upper southern sector of the volcano. The eruption was preceded by a large earthquake swarm for a few days before its onset and accompanied by ground deformation and fracturing. The development of surface cracking along with the seismic pattern has allowed us to recognize three distinct eruptive systems (the SW–NE, NNW–SSE and N–S systems) which have been simultaneously active. Such eruptive systems are only the upper portions of a complex feeding system that was fed at the same time by two distinct magmas. The SW–NE and NNW–SSE systems, connected with the SE crater conduit, were fed by magma coming from depth, whereas the N–S system served instead as an ascending pathway for an amphibole-bearing magma residing in a shallow reservoir. The eruptive activity started again on October 2002 on the NE Rift Zone, where about 20 eruptive vents were aligned between 2500 and 1900 m a.s.l., and on the southern flank, from the central crater to the Montagnola. The onset of eruptive activity was accompanied by a seismic swarm. As in the 2001 eruptive event, two independent feeding systems formed, characterized by distinct magmas. The SW–NE system controlled the feeding of the Northeast Rift and was accommodated by left-lateral displacement along the WNW–ESE trending Pernicana Fault. The N–S system fed the eruptions on the southern flank. Moreover, the associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano and offshore. These two last eruptions indicate that at Mt. Etna the ascent of magma, as well as the accommodation of deformation, is strongly dominated by local extensional structures that are connected to a regional tectonic regime.

Description: Published

Description: 211-233

Description: partially_open

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: 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: Multichannel reflection seismic data were acquired south of the Salento peninsula, in an area where crustal seismicity has been recorded. Seismic profiles show the presence of small grabens bounded by extensional faults with NW-SE direction. These grabens are filled with Plio-Quaternary sediments and represent the prolongation of the grabens located onshore in the Salento peninsula. Outer arc extension due to flexuring of the Adriatic-Apulian lithosphere under the double load of the Hellenides and Apennines-Calabrian arc is thought to have originated these grabens. The Adriatic-Apulian continental lithosphere presents a very small radius of curvature and a decoupling between upper crust and mantle lithosphere is expected. Inner arc compression within the upper crust may be responsible for the seismicity recorded in the area.

Description: JCR Journal

Description: open

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: The North Tabriz Fault is a major seismogenic fault in NW Iran. The last damaging earthquakes on this fault occurred in 1721, rupturing the southeastern fault segment, and in 1780, rupturing the northwestern one. The understanding of the seismic behavior of this fault is critical for assessing the hazard in Tabriz, one of the major cities of Iran; the city suffered major damage in both the 1721 and 1780 events. Our study area is located on the northwestern fault segment, west of the city of Tabriz. We performed geomorphic and trenching investigations, which allowed us to recognize evidence for repeated faulting events since the Late Pleistocene. From the trenches, we found evidence for at least four events during the past 3.6 ka, the most recent one being the 1780 earthquake. On the basis of different approaches, horizontal slip per event and slip rates are found in the ranges of 4 ± 0.5 m and 3.1-6.4 mm/yr, respectively. We also attempted an estimate of the average recurrence intervals which appears to be in the range 350-1430 years, with a mean recurrence interval of 821 ± 176 years. On the basis of these results, the northwestern segment of the North Tabriz Fault does not appear to present a major seismic potential for the near future, however, not enough is known about the southeastern segment of the fault to make a comparable conclusion.

Description: Published

Description: JCR Journal

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: Two major deformation belts occur in the portion of the Adriatic Sea offshore the Gargano Promontory. Although these two belts display similar characters on seismic profiles, they are different in other respects. The NE-SWtrending Tremiti Deformation Belt, located north of the Gargano Promontory, originated during the Plio-Quaternary, while the E-W-trending South Gargano Deformation Belt, located south of the Gargano Promontory, formed in a time span that goes from Eocene to early Pliocene. On the ground of structural and stratigrafic evidence these deformation belts are interpreted as originated by tectonic inversion of Mesozoic extensional faults. This inversion tectonics, of Tertiary age, can be related to the evolution of the fold-and-thrust belts that surround the Adriatic Sea. A moderate seismic activity, recorded around the Tremiti Island, and historical seismological data suggest that the whole of study area is, at present, seismically active. Therefore, this portion of the Adriatic block still represents a preferental site of deformation.

Description: Published

Description: 229-247

Description: JCR Journal

Description: open

Description: L'evoluzione tettonica delllAdriatico meridionale à stata studiata attraverso l'interpretazione di profili sismici a riflessione e l'analisi di pozzi per l'esplorazione. Durante il Mesozoico quest'area à stata interessata dal processo di rifting che ha portato all'apertura della Tetide. Questa tettonica estensionale ha generato un bacino pelagico epicontinentale bordato da piattaforme carbonatiche, il cui margine sud-occidentale à tracciabile con l'ausilio dei profili sismici. L'area di piattaforma e quella bacinale si comportano in maniera diversa quando coinvolte nell'orogenesi alpina. Nel Cenozoico l'Adriatico meridionale diventa un bacino di avanfossa legato alla catena Ellenico-Dinarica, il cui fronte à presente in prossimità della costa albanese. Lungo tale fronte, che à tuttora sismicamente attivo, sono presenti delle marcate differenze di stile strutturale che sembrano imputabili alla strutturazione mesozoica in piattaforma e bacino. Il bacino di avanfossa contiene sedimenti clastici oligocenico-quaternari e gli spessori massimi, fino a 8-10 km, si trovano al disopra delle aree bacinali mesozoiche. Nei pressi della costa pugliese e in particolare a sud del promontorio garganico, in posizione di avampaese rispetto alla catena albanese, si osservano strutture plicative legate a faglie inverse. Si ritiene che tali strutture, di età eocenica- pliocenica inferiore, siano dovute alla propagazione in avampaese di sforzi compressivi originatisi nelle zone di catena.

Description: Published

Description: 227-237

Description: open

Description: We describe the evolution of the volcanic activity and deformation patterns observed at Mount Etna during the July–August 2001 eruption. Seismicity started at 3000 m below sea level on 13 July, accompanied by moderate ground swelling. Ground deformation culminated on 16 July with the development of a NE–SW graben c. 500 m wide and c. 1 m deep in the Cisternazza area at 2600–2500 m above sea level on the southern slope of the volcano. On 17 July, the eruption started at the summit of Mount Etna from the SE Crater (central–lateral eruptive system), from which two radial, c. 30 m wide, c. 3000 m long fracture zones, associated with eruptive fissures, propagated both southward (17 July) and northeastward (20 July). On 18 July, a new vent formed at 2100 m elevation, at the southern base of the Montagnola, followed on the next day by the opening of a vent further upslope, at 2550 m (eccentric eruptive system). The eruption lasted for 3 weeks. Approximately 80% of the total lava volume was erupted from the 2100 m and the 2550 m vents. The collected structural data suggest that the Cisternazza graben developed as a passive local response of the volcanic edifice to the ascent of a north–south eccentric dyke, which eventually reached the ground surface in the Montagnola area (18–19 July). In contrast, the two narrow fracture zones radiating from the summit are interpreted as the lateral propagation, from the conduit of the SE Crater, of north–south- and NE–SW-oriented shallow dykes, 2–3 m wide. The evolution of the fracture pattern together with other volcanological data (magma ascent and effusion rate, eruptive style, petrochemical characteristics of the erupted products, and petrology of xenoliths within magma) suggest that the eccentric and central–lateral eruptions were fed by two distinct magmatic systems. Examples of eccentric activity accompanied by central–lateral events have never been described before at Etna.

Description: Published

Description: 531-544

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

Description: 3.2. Tettonica attiva

Description: 3.5. Geologia e storia dei sistemi vulcanici

Description: 3.6. Fisica del vulcanismo

Description: JCR Journal

Description: reserved

Description: The Tindari Fault System (southern Tyrrhenian Sea, Italy) is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab. Onshore structural data, an offshore seismic reflection profile, and earthquake data are analyzed to constrain the present geometry of the Tindari Fault System and its tectonic evolution since Neogene, including the present seismicity. Results show that this zone of deformation consists of a broad NNW trending system of faults including sets of right-lateral, left-lateral, and extensional faults as well as early strike-slip faults reworked under late extension. Earthquakes and other neotectonic data provide evidence that the Tindari Fault System is still active in the central and northern sectors and mostly accommodates extensional or rightlateral transtensional displacements on a diffuse array of faults. From these data, a multiphase tectonic history is inferred, including an early phase as a right-lateral strike-slip fault and a late extensional reworking under the influence of the subductionrelated processes, which have led to the formation of the Tyrrhenian back-arc basin. Within the present, regional, geodynamic context, the Tindari Fault System is interpreted as an ongoing accommodation zone between the adjacent contractional and extensional crustal compartments, these tectonic compartments relating to the complex processes of plate convergence occurring in the region. The Tindari Fault System might also be included in an incipient, oblique-extensional, transfer zone linking the ongoing contractional belts in the Calabrian-Ionian and southern Tyrrhenian compartments.

Description: Published

Description: TC2006

Description: reserved

Description: The present-day tectonic setting of the Italian peninsula is very complex and involves competing geodynamic processes. In this context, southern peninsular Italy is characterised by extension along the Apenninic belt and in the Tyrrhenian margin and by transpression in the Apulia-Gargano region. The extension is well defined by means of geological, seismological, and contemporary stress data. For the latter only few data are available in the Apulia-Gargano region, leaving the state of stress in that area unresolved. Here we develop a finite-element model of the southern Italian region in order to predict the contemporary stress field. Our model predictions are constrained by model-independent observations of the orientation of maximum horizontal stress (SHmax), the tectonic regime, and the horizontal velocities derived from GPS observations. We performed a blind test with 31 newly acquired SHmax orientations in the Southern Apennines. These new data come from the analysis of borehole breakouts performed in 46 deep oil exploration wells ranging in depth from 1300 to 5500 m. The model results agree with the stress data that define a prevailing NW-SE SHmax orientation along the Apenninic belt and foredeep and thus are capable to predict the stress field where no stress information is available. We first analyse how much model predictions, based on older data, deviate from present-day stress data and then recalibrate the models based on our new stress data, giving insight into the resolution of both models and data. In the studied region, which is affected by low deformation rates, we find that geodetic data alone cannot resolve such low levels of deformation due to the high relative measurement errors. We conclude that both GPS and stress data are required to constrain model results.

Description: This research was supported by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC) through the INGV-DPC project S1.

Description: Published

Description: 193-204

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

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: 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: In this paper we describe evidence of strong tectonic deformation affecting two aqueducts of Roman age (II–III century A.D.). The channels are located approximately 20 km northeast of Rome along the ancient Via Tiburtina. Brittle and ductile deformation affects these two structures, including extensional joint systems, NE-oriented faults, and horizontal distortion. This deformation is consistent with rightlateral movement on major N-striking faults, and represents the first evidence that tectonic deformation took place in historical times in the vicinity of Rome, with local strike–slip movement superimposed on a regional extensional fault system.

Description: Published

Description: 679–690

Description: reserved

Description: The active tectonics at the front of the Southern Apennines and in the Adriatic foreland is characterized by E-W striking, right-lateral seismogenic faults, interpreted as reactivated inherited discontinuities. The best studied among these is the Molise-Gondola shear zone (MGsz). The interaction of these shear zones with the Apennines chain is not yet clear. To address this open question we developed a set of scaled analogue experiments, aimed at analyzing: 1) how dextral strike-slip motion along a pre-existing zone of weakness within the foreland propagates toward the surface and affects the orogenic wedge; 2) the propagation of deformation as a function of displacement; 3) any insights on the active tectonics of Southern Italy. Our results stress the primary role played by these inherited structures when reactivated, and confirm that regional E-W dextral shear zones are a plausible way of explaining the seismotectonic setting of the external areas of the Southern Apennines.

Description: INGV, Università degli Studi di Pavia

Description: Published

Description: 21

Description: open

Description: The Global Paleomagnetic Database (GPMDB), now updated to 1992, contains about 7000 paleomagnetic data, which are fundamental tools to define regional and global geodynamic models. A software developed at the Istituto Nazionale di Geofisica Allows the selection of data on the basis of space, time, and quality. Six quality classes have been proposed. The African and European Apparent Polar Wander Paths (APWPs) have been computed and the role of the statistical uncertainties is discussed. Some examples from the Tethys Belt have been chosen to demonstrate the effect of the quality filtering in geodynamic studies.

Description: Published

Description: 225-237

Description: open

Description: Due to the apparent deformation field heterogeneity, the stress regimes around the Provence block, from the fronts of the Massif Central and Alpine range up to the Ligurian Sea, were not well defined. To improve the understanding of the SE France stress field, we determine new earthquake focal mechanisms and we compute the present-day stress states by inversion of the 89 available focal mechanisms around the Provence domain, including the 17 new ones calculated in the current study. This study provides evidence of 6 different deformation domains around the Provence block with different tectonic regimes. On a regional scale, we identify three zones characterised by significantly different stress regimes: a western one affected by an extensional stress (normal faulting) regime, a southeastern one characterised by a compressional stress (reverse to strike-slip faulting) regime with NNW- to WNW-trending σ1 and a northeastern one, i.e., the Digne nappe front, marked by an NE-trending compression. Note that the Digne nappe back domain is controlled by an extensional regime that is deforming the western alpine core. This extensional regime could be a response to buoyancy forces related to the Alpine high topography. The stress regimes in the southeast of the Argentera Massif and around the Durance fault are consistent with a coherent NNW-trending σ1 that implies a left-lateral component of the active reverse oblique-slip of the Moyenne Durance Fault. In the Rhone Valley, an E-trending extension characterises the tectonic regime that implies a normal component of the present-day Nîmes fault displacement. This study provides evidence for short-scale variation of the stress states that reflect abrupt change in the boundary force influences on upper crustal fragments (blocks). These spatial stress changes around the Provence block result from the coeval influence of forces applied at both its extremities, i.e., in the north-east, the Alpine front push and in the southeast, the northward African plate drift. Besides these boundary forces, the influence of the mantle plume under the Massif Central can be superimposed along the western block boundary.

Description: Published

Description: 336-348

Description: partially_open

Description: We relocate the 1990–1991 Potenza (Southern Apennines belt, Italy) sequences and calculate focal mechanisms. This seismicity clusters along an E–W, dextral strike–slip structure. Secondorder clusters are also present and reflect the activation of minor shears. The depth distribution of earthquakes evidences a peak between 14 and 20 km, within the basement of the subducting Apulian plate. The analysed seismicity does not mirror that of Southern Apennines, which include NW–SE striking normal faults and earthquakes concentrated within the first 15 km of the crust. We suggest that the E–W faults affecting the foreland region of Apennine propagate up to 25 km of depth. The Potenza earthquakes reflect the reactivation of a deep, preexisting fault system. We conclude that the seismotectonic setting of Apennines is characterized by NW–SE normal faults affecting the upper 15 km of the crust, and by E– W deeper strike–slip faults cutting the crystalline basement of the chain.

Description: Published

Description: 586-590

Description: N/A or not JCR

Description: reserved

Description: We modeled Pnl phases from several moderate magnitude earthquakes in the eastern Mediterranean to test methods and develop path calibrations for determining source parameters. The study region, which extends from the eastern part of the Hellenic arc to the eastern Anatolian fault, is dominated by moderate earthquakes that can produce significant damage. Our results are useful for analyzing regional seismicity as well as seismic hazard, because very few broadband seismic stations are available in the selected area. For the whole region we have obtained a single velocity model characterized by a 30 km thick crust, low upper mantle velocities and a very thin lid overlaying a distinct low velocity layer. Our preferred model proved quite reliable for determining focal mechanism and seismic moment across the entire range of selected paths. The source depth is also well constrained, especially for moderate earthquakes.

Description: Published

Description: N/A or not JCR

Description: reserved

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: This study concerns the unstable scarp named Sciara del Fuoco (SDF) at Stromboli volcano, merging geostructural observations, live-cam records in the visible and IR bands, analysis of vertical aerial photographs, and seismic records. These are used to assess morpho-structural changes between 2002 and 2004. The onset of the lava effusion on 28 December, 2002 preceded a gravitational collapse by two days, affecting a wide area of the SDF above and below sea level. We surmise that the collapse enhanced latent instability of the scarp. The 2002–2003 lava flows had a remarkable stabilizing effect on wide portions (〉50%) of the SDF, whilst erosive phenomena continued in the zone not covered by lava. This caused unrelenting regression of the upper landslide scarp toward the summit craters in the form of rockfalls and debris flows. If the crater conduit were involved in the sliding, then a change in eruptive behavior cannot be excluded.

Description: Published

Description: L09304

Description: reserved

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: We revisited data related to the 1456 seismic crisis, the largest earthquake to have ever occurred in peninsular Italy, in search of its causative source(s). Data about this earthquake consist solely of historical reports and their intensity assessment. Because of the age of this multiple earthquake, the scarcity and sparseness of the data, and the unusually large damage area, no previous studies have attempted to attribute the 1456 events to specific faults. Existing analytical methods to identify a likely source from intensity data also proved inappropriate for such a sparse dataset, since historical evidence suggests that the cumulative damage pattern contains at least three widely separated events. We subdivided the 1456 damage pattern into three independent mesoseismal areas; each of these areas falls onto east–west tectonic trends previously identified and marked by deep (〉10 km) right-lateral slip earthquakes. Based on this evidence we propose (1) that the 1456 events were generated by individual segments of regional east–west structures and are evidence of a seismogenic style that involves oblique dextral reactivation of east–west lower crustal faults; (2) that each event may have triggered subsequent but relatively distant events in a cascade fashion, as suggested by historical accounts; hence (3) that the 1456 sequence reveals a fundamental but unexplored mechanism of tectonic deformation and seismic release in southern Italy. This style dominates the region that lies between the northwest–southeast system of large extensional faults straddling the crest of the southern Apennines and the buried outer front of the chain. Although the quality of the available information concerning the 1456 earthquake is naturally limited, we show that the overlap of the damage distribution, the orientation and characteristics of regional tectonic structures, the seismicity patterns, and the focal mechanisms all concur with our interpretations and would be difficult to justify otherwise.

Description: Published

Description: 725-748

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: open

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: 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: Is compression across the northern Apennine fold-and-thrust system (Italy) still active? To address this question, we quantified the long-term rates of migration and shortening of the system along with the measurement errors. Our approach integrates structural geology, seismicity patterns, and statistical treatment of tectonic activity. On the basis of recently published surface and subsurface data, we found a migration rate of 8.85 ± 0.61 mm/yr. The inception age of individual fold structures follow closely this average rate, indicating that the system has been migrating at a constant rate for the past 17 Myr. Cumulative shortening of the system also increases linearly through time at 2.93 ± 0.31 mm/yr. The location of the youngest structures in the easternmost portion of the system coincides with a significant peak of seismic moment released by historical earthquakes. We conclude that not only these easternmost thrusts are still active, but also that they generate earthquakes.

Description: Regione Marche

Description: Published

Description: 462–468

Description: 3.2. Tettonica attiva

Description: JCR Journal

Description: partially_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: L’area del terremoto dell’Irpinia del 1930 corrisponde in profondità all'avampaese Apulo, inflesso al di sotto delle unità alloctone accavallate nella porzione frontale del cuneo orogenico, ma non coinvolto nelle strutture dei cosiddetti duplex dell'Apula sensu Patacca and Scandone (2004). In particolare, le profondità ipocentrali del terremoto del 1930 corrispondono al basamento sottostante la successione della Piattaforma Carbonatica Apula. Il campo macrosismico e i dati strumentali disponibili (si veda la sorgente in DISS, 2007, con relativa bibliografia, e Pino et al., sottomesso) suggeriscono una sorgente sismogenetica con un’orientazione e una cinematica che rappresentano una sorta di transizione tra la direzione W-E a cinematica trascorrente destra, che caratterizza la sismicità propria delle aree di avampaese sia affiorante che sepolto, e la direzione NW-SE a cinematica normale, che caratterizza la sismicità connessa all'estensione lungo l'asse della catena Appenninica (si veda il terremoto del 1980). In questo quadro, l’obiettivo dello studio magnetotellurico è stato quello di investigare i volumi di crosta al di sotto della successione Apula per valutare l'eventuale presenza di direzioni preferenziali dell'anisotropia di resistività che fossero confrontabili con la direzione della sorgente del terremoto del 1930. Il verificarsi di tale evenienza avrebbe potuto essere infatti interpretato come indizio di una zona di debolezza regionale, che avrebbe condizionato le caratteristiche geometriche e cinematiche della sorgente del terremoto stesso. Partendo dall’area sismogenetica segnalata nel DISS per questo terremoto, sono stati effettuati in un’area di circa 1000 km2 sondaggi magnetotellurici in 15 siti, nell’intervallo di 0.009- 4000 s. Per ciascun sito si è proceduto alla misura delle tre componenti ortogonali del campo magnetico e di tre componenti del campo elettrico, di cui due lungo la stessa linea e ortogonali alla terza. Ciò ha consentito la stima dei parametri magnetotellurici per due sondaggi adiacenti, al fine di meglio controllare possibili problemi di rumore antropico o strumentale. Le stazioni, fino ad un massimo di tre, hanno operato in contemporanea fungendo l’una per l’altra da remote reference (Gamble et al., 1979). Va sottolineata la buona qualità dei dati acquisiti sia in termini di stime stabili con diverse tecniche di analisi, che per basso scattering delle curve di resistività apparente e fase. Le risposte sperimentali sono state poi comparate con i dati di pozzo disponibili, verificando un ottimo accordo. È stata inoltre eseguita un’analisi sulle proprietà fisiche e geometriche del tensore impedenza, adottando lo schema di decomposizione di Weaver et al. (2000) dal quale è derivato poi lo studio degli invarianti magnetotellurici per la definizione della dimensionalità delle strutture elettriche investigate ai vari periodi (ovvero alle varie profondità). Circa il 75% dei dati analizzati implica strutture assimilabili necessariamente a modelli tridimensionali e le quattro componenti del tensore impedenza sono significativamente diverse da zero. Per questo tipo di strutture, seguendo Weaver et al. (2000), è comunque possibile definire una direzione di eterogeneità elettrica. Ciò è stato fatto per ciascun sondaggio e per ciascun periodo di stima. Mediante la trasformazione di Niblett–Bostick è stato poi ottenuto lo strike elettrico in funzione della profondità stimata. Viene riportata la direzione di strike per i vari sondaggi alla profondità stimata nell’intervallo 8 - 16 km, riferibile quindi a una porzione di crosta al di sotto del resistivo che identifica le successioni della Piattaforma Apula.

Description: Unpublished

Description: CNR, P.le Aldo Moro 7, Roma, Italia

Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive

Description: open

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: Tectonic activity in convergent plate boundaries commonly involves backward migration (rollback) of narrow subducting slabs and segmentation of subduction zones through slab tearing. Here we investigate this process in the Italian region by integrating seismic tomography data with spatio-temporal analysis of magmatic rocks and kinematic reconstructions. Seismic tomography results show gaps within the subducting lithosphere, which are interpreted as deep (100-500 km) sub-vertical tear faults. The development of such tear faults is consistent with proposed kinematic reconstructions, in which different rates of subduction rollback affected different parts of the subduction zone. We further suggest a possible link between the development of tear faults and the occurrence of regional magmatic activity with transitional geochemical signatures between arc-type and OIB-type, associated with slab tearing and slab breakoff. We conclude that lithospheric- scale tear faults play a fundamental role in the destruction of subduction zones. As such, they should be incorporated into reconstructions of ancient convergent margins, where tear faults are possibly represented by continental lineaments linked with magmatism and mineralization.

Description: Unpublished

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

Description: JCR Journal

Description: open

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: In October and November 2002, the Molise region (southern Italy) was struck by two moderate magnitude earth- quakeswithin 24 hours followed by an onemonth long aftershocks sequence. Soon after the ?rstmainshock (October 31st, 10.32 UTC, Mw 5.7), we deployed a temporary network of 35 three-component seismic stations. At the time of occurrence of the second main event (November 1st, 15.08 UTC, Mw 5.7) the eight local stations already installed allowed us to well constrain the hypocentral parameters. We present the location of the two mainshocks and 1929 aftershocks with 2 〈 ML 〈 4.2. Earthquake distribution reveals a E-trending 15 km long fault system composed by two main segments ruptured by the two mainshocks. Aftershocks de?ne two sub-vertical dextral strike-slip fault segments in agreementwith themainshock fault plane solutions. P- and T -axes retrieved from170 aftershocks focal mechanisms show a coherent kinematics: with a sub-horizontal NW and NE-trending P and T -axes, respectively. Fora small percentage of focal mechanisms (~10%) a rotation of T axes is observed, resulting in thrust solutions. The Apenninic active normal fault belt is located about 80 km westward of the 2002 epicentral area and signi?cant seismicity occurs only 20-50 km to the east, in the Gargano promontory. Seismic hazard was thought to be small for this region because neither historical earthquake are reported in the Italian seismic catalogue or active faults were previously identi?ed. In this context, the 2002 seismic sequence highlights the existence of trans-pressional active tectonics in between the extensional Apenninic belt and the Apulian foreland.

Description: Published

Description: 487-494

Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale

Description: JCR Journal

Description: reserved

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: 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: 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: 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: Panarea, characterized by gas unrest in 2002–2003, is the volcanic island with the least constrained structure in the eastern-central Aeolian Arc (Italy). Based on structural measurements, we define here its deformation pattern relative to the Arc. The main deformations are subvertical extension fractures (63% of data), normal faults (25%) and dikes (12%). The mean orientation of the extension fractures and faults is ∼N38◦E, with a mean opening direction of N135◦ ±8◦, implying extension with a moderate component of dextral shear. These data, matched with those available for Stromboli volcano (pure opening) and Vulcano, Lipari and Salina volcanoes (predominant dextralmotions) along the eastern-central Arc, suggest a progressivewestward rotation of the extension direction and an increase in the dextral shear. The dextral shear turns into compression in the western arc. The recent unrest at Panarea, coeval to that of nearby Stromboli, may also be explained by the structural context, as both volcanoes lie along the portion of the Arc subject to extension.

Description: Protezione Civile, project INGV-DPC-V2

Description: Published

Description: 288-292

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

Description: 3.2. Tettonica attiva

Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi

Description: 3.6. Fisica del vulcanismo

Description: JCR Journal

Description: reserved

Description: In the text

Description: Osservatorio Vesuviano

Description: Published

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

Description: open

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: In the text

Description: Osservatorio Vesuviano

Description: Published

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

Description: open

Description: This document illustrates in details the raw structure of the Database of Individual Seismogenic Sources, version 3 [Basili et al., 2008; http://diss.rm.ingv.it/diss/] - hereinafter referred to as the Database – and is dedicated at instructing any potential contributor, outside the DISS Working Group, on how to populate it with new seismogenic sources. It is worth of notice that the primary purpose of the Database is to provide a seismogenic source model at regional scale. It is hence usually populated by filling in large regions at once, not record by record.

Description: INGV, Roma1

Description: Published

Description: 3.2. Tettonica attiva

Description: open

Description: The transition between the central and southern Apennines (Italy) is marked, among other regional features, by a dramatic shift (from SW-dipping to NE-dipping) of the verging of the large (25+ km long) seismogenic normal faults, responsible for M〉6 pre-historical and historical earthquakes. Also, in the exact area where such accommodation occurs, in 2005 a low magnitude (M〈3) seismic sequence took place along a short stretch of a long-lived transverse structure Running across this transition zone. We believe this sequence sheds light on the geometry and the role of the interaction between these seismogenic domains.

Description: Submitted

Description: 3.2. Tettonica attiva

Description: N/A or not JCR

Description: open

Description: We investigated quantitatively the propagation of a reactivated strike-slip fault through a sedimentary cover. To this end we prepared five simplified analogue models that reproduce a chain with its frontal allochtonous wedge overrunning the foreland. The foreland/ chain deformation follows the reactivation of an inherited strike-slip fault cutting the foreland domain. The observation and quantification of the effects of this reactivation, in particular on the orogenic wedge front, provide new insight on the evolution of this type of tectonic setting. We placed special emphasis on quantifying the structural features observed in the models to (1) interpret the kinematics of the reactivated shear zone, and (2) put forward hypotheses on areas indirectly affected by the reactivated fault. The interpretation of the models was based on an integrated analysis of surface and subsurface data. The results show that the geological setting is strongly influenced by the presence of a reactivated preexisting lineament, that ultimately controls the development and pattern of newly-formed faults. Finally, we present and discuss two natural examples (in Italy Molise-Gondola shear zone, Southern Apennines, and Scicli-Ragusa line, Sicily) in view of the modeling results.

Description: Published

Description: 107-122

Description: 3.2. Tettonica attiva

Description: JCR Journal

Description: 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: The active tectonics of the Southern Apennines of Italy (Calabrian Arc excluded) is mainly characterized by SW-NE extension, which accounts for large earthquakes generated by NW-SE striking normal faults. However, the 2002 Molise earthquakes occurred along an E-W striking right-lateral seismogenic structure located to the NE of the Southern Apennines axis. This and other lines of evidence suggested that the frontal part of the chain and the adjacent foreland are affected by E-W striking, right-lateral active faults systems. The 2002 Molise seismic sources, in particular, are located along the western part of a regional fault system, the Molise-Gondola shear zone (MGsz). On land, this system is mainly represented by the Mattinata Fault, an important structure of the foreland that has already been intensely investigated from a regional, structural and seismotectonic point of view. A polyphase activity (since Mesozoic times) has been recognized, and the complex fault kinematics is still matter of debate. Nevertheless, most investigators agree on a present-day activity with right-lateral sense of motion, as confirmed by the focal mechanism of the 19 June 1975 earthquake, GPS data, geomorphological and paleoseismological investigations. Indeed, the Mattinata Fault has already been interpreted as the source of historical earthquakes (e.g., 493 AD, 1875), and instrumental seismicity is normally recorded within the first 25 km of the crust of the Gargano area. These data indicate that inherited E-W striking high-angle fault systems are solicited under the present-day stress field. Off-shore the Gargano Promontory, the Mattinata Fault seems to be aligned with a regional (ca. 150 km in extent) E-W to NW-SE oriented deformation belt (known in the literature as Gondola Line), including a main fault and fold system known as Gondola Fault and Gondola Ridge, respectively. In the past, this structure has been investigated using multi-channel seismic reflection profiles and well-log data. Several investigators proposed a Mesozoic origin for the Gondola Line, followed by a complex pattern of repeated re-activation during the Cenozoic. Kinematics and timing of post-Mesozoic re-activation are still debated; however, most investigators agree that only deposits older than Miocene appear severely deformed, whereas Plio-Pleistocene units yield little or no deformation at all. This multi-history deformation pattern shown along the Gondola Line closely resembles the long-term complex evolution recorded along the Mattinata Fault, except for the lack of significant seismicity. Therefore, although one could expect the Gondola Line to be subjected to the same stress field responsible for recent re-activation of the Mattinata Fault, direct evidence is not available from historical and present-day seismicity. However, in recent years, evidence of recent tectonic deformation off-shore Gargano has arisen from very-high resolution seismic stratigraphy based on a dense grid of Chirp-Sonar profiles. These data allowed the identification of low amplitude fold systems and shallow sub-vertical faults propagating in middle-late Pleistocene and Holocene deposits, particularly along the E-W (on the continental shelf) and NW-SE (on the slope) segments of the Gondola Line. Several of these faults either affect Holocene units younger than 5.5 ka (based on bio-chronostratigraphic analyses from core samples), or even offset the seafloor. Altogether, both recent seismicity related to E-W dextral strike-slip tectonics along the westernmost part of the MGsz and along the Mattinata Fault itself, and very recent (〈 5.5 ka) deformation features along the Gondola Line, suggest that the MGsz as a whole is being actively deformed, although variably along-strike. In order to verify this hypothesis, we attempt a comparison between on- and off-shore data supporting recent activity along E-W oriented foreland structures. The integration of such heterogeneous yet complementary datasets may contribute to discuss late Quaternary tectonics of the Southern Apennines foreland domain, and provide comprehensive (on-shore / to / off-shore) scenarios for investigating recent / active tectonics of the MGsz and evaluating its possible seismogenic character.

Description: Unpublished

Description: Vienna International Center Vienna Austria

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: The difference between the value of seismic moment computed using the surface wave data and the value derived from the normal modes of the Earth requires reinterpretation of the focal mechanism of the Great Sumatran Earthquake (TU=26 December 2004 - 00h 58m, Lat=3.3°N, Lon=95.8°E, H=30 km, M=9.3) based on the second conjugate – near vertical CMT fault plane solution. The displacement of the Earth’s instantaneous rotation pole – observed at ASI of Matera, Italy –, the seismic data (USGS) in the two days following the main shock, the high frequency P-wave radiation, the geomorphologic data, and the satellite data of uplift/subsidence of the coasts (IGG) converge toward this interpretation. A thorough revision or a complete overcoming of the subduction concept is then needed.

Description: Published

Description: 8-23

Description: open

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: The basic idea of this thesis is to exploit the capabilities of neural networks in a very new framework: the quantitative modelling of the seismic source and the interferogram inversion for retrieving its geometric parameters. The problem can be sum up as follows. When a moderateto- strong earthquake occurs we can apply SAR Interferometry (InSAR) technique to compute a differential interferogram. The latter is used to detect and measure the surface displacement field. The earthquake has been generated by an active, seismogenic, fault having its own specific geometry. Therefore each differential interferogram contains the information concerning the geometry of the seismic source the earthquake comes from; its shape and size, the number of fringes, the lobe orientation and number are the main features of the surface effects field. Two problems have been analysed in this work. The first is the identification of the seismic source mechanism. The second is a typical inversion exercise concerning the fault plane parameter. To perform both exercises of the seismic fault a huge number of synthetic interferograms has been computed. Each of them is generated by a different combination of such geometric parameters. As far as the retrieval of the geometric parameters is concerned an artificial neural network has been properly generated and trained to provide an inversion procedure to single out the geometric parameters of the fault. Five among these latter, Length, Width, Dip, Strike, Depth, have been simultaneously inverted. The result is in agreement with those results based on different approaches. Furthermore the method seems very promising and leads to improve the studies concerning the combined use of neural networks and InSAR technique.

Description: Tor Vergata University

Description: Unpublished

Description: open

Description: Sicily is characterised by active deformations, as suggested by the presence of very recent faulted deposits and by widespread seismicity. The northern portion of the Sicilian belt has undergone strike-slip tectonics since the Pliocene, as the effect of the south Tyrrhenian border dynamics. Integrated methodologies of analysis have been utilised to evaluate the neotectonic setting of the northern sector of the island. To this aim, we have elaborated mesostructural, morphotectonic and morphometric data obtained from field survey, photogeological analysis and from the elaboration of digital elevation model (DEM) data relative to 31 drainage basins. The data sets have been compared with the uplift rate and seismicity distributions, allowing us to recognise different crustal blocks into which the northern Sicily chain may be divided. Each block of the chain reflects the characteristic morphometric pattern of the drainage basins. The morphostructural setting, the distribution of seismicity and the orientation of the recent faults indicate that the main narrow neotectonic deformation zones bounding the crustal blocks range from NW-SE, NE-SW and W-E.

Description: Published

Description: 221-244

Description: JCR Journal

Description: open

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: The statistical analysis of stream orientations is an helpful tool in the active tectonic studies because the rivers network is an important geomorphologic feature useful to derive the deformation due to active faults. The drainage network automatically derived from DTM’s is not generally usable for this type of analysis because the automatic routines generate the stream network following the four direction orthogonal to the cell. In this paper we present a semiautomatic methodology to extract the drainage network from high resolution DTM data (5x5 pixel m) the most possible consistent with the real water-drainage pattern, in order to make accurate statistic azimuthal analyses of stream orientations. The methodology have been tested on the active tectonic area of the Tammaro basin (Campania and Molise Regions), epicentral zone of the 1688 strong earthquake (MW=6.7). The results obtained by the application of the proposed methodology show a good agreement with the drainage pattern map derived from photo-interpretation (Regional Technical Cartography).

Description: Published

Description: Centro Congressi Lingotto, Torino

Description: 5.4. TTC - Sistema Informativo Territoriale

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: In a recent paper we compared the earthquake hypocenters, plotted according to updated catalogs, with the structure of the earth’s Crust interpreted after the results of seismic exploration (mainly the Deep Seismic Soundings – DSS). The comparison was made along several cross sections in the Alpine range, the Italian Peninsula and the surrounding seas. The main conclusions of this analysis were that 1) the majority of the events is positioned in the upper, rigid crust and 2) the earthquakes tend to concentrate above the discontinuities unveiled by the seismic exploration in the deep crust and at the Moho boundary. With the goal to shed some light on the continuation of these structures with depth, in this paper a similar analysis is conducted even in volumes where DSS information are not available. It is apparent that the upper mantle seismicity is very unevenly distributed; therefore we only focus on the areas where a sub-crustal seismicity is recorded, adding to the seismic models of the crust some information, if available, on the physical characters of the upper Lithosphere. Four areas are examined: the well known Calabrian (Aeolian) Arc where the Ionian plate is subducted beneath the Tyrrhenian, thin crust of oceanic type, the active subduction of the slab being witnessed by deep and very deep earthquakes; the north-central Apennines where the continental crust of the Adria microplate seems also subducted beneath the transitional, peri-Tyrrhenian type of crust but where the observed hypocenters are limited to the depth of about 100 km; the northern Apennines, where the same type of subduction seems to occur beneath the north-eastern slope of the mountain range, though evidenced by an even smaller number of events; finally, the western Alps: also here a small group of foci are recorded in the upper Mantle beneath the southern end of the “Ivrea body”. The different behavior of deep seismicity in the four areas confirms that the Italian peninsula is formed of sectors deriving from different geodynamical processes.

Description: Published

Description: 99-114

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

Description: JCR Journal

Description: partially_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: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

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

Description: open

Description: Field geology, well data and seismic imaging have illuminated the upper crustal structure of the Southern Apennines. However, lack of control of the deep structure allows viable competing thin-skin and thick-skin models of the orogen. In thin-skin models the detachment decouples a stack of rootless nappes from the basement. In thick-skin models, basement is involved in the most recent phase of thrusting. To examine the deep crustal structure, we use the teleseismic recordings from the CAT/SCAN array, deployed in southern Italy from Dec. 2003-Oct. 2005. We use receiver functions processed into a Common Conversion Point stack to generate images of the crust. We image three main westward-dipping seismic-velocity discontinuities where P-to-S conversions occur. They correspond to velocity jumps at the Moho, the upper-lower crust boundary and sedimentary interfaces resulting from the contrast between clastic and carbonate strata with basement. The CCP image matches features from both thin-skin and thick skin model. The lateral continuity of the converters favors thin skin, but consistent interpretation across the image favors the thick skin. Overall, the results provide a better fit to the thick-skin interpretation. This suggests a change in structural style as the collision with Apulia halted motion. This model also implies considerably less Plio-Pleistocene shortening across the Apennines and a SE motion of the Calabrian Arc subparallel to the southern Apennines rather than a radial expansion of the Arc.

Description: Published

Description: AGU General Assembly, S. Francisco

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

Description: open

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

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

Description: open

Description: Published

Description: 3.10. Sismologia storica e archeosismologia

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

Description: 5.8. TTC - Formazione e informazione

Description: open

Description: In the framework of the 2004 reference seismic hazard map of Italy the amplitude of the strong-motion (expressed in terms of Peak Horizontal Acceleration with 10% probability of non-exceedence in 50 years, referred to average hard ground conditions) was computed using different predictive relationships. Equations derived in Italy and in Europe from strong-motion data, as well as a set of weak and strong-motion based empirical predictive relationships were employed in a logic tree procedure, in order to capture the epistemic uncertainty affecting ground-motion attenuation. This article describes the adjustments and conversions required to eliminate the incompatibilities amongst the relations. Particularly significant are distance conversions and style-of-faulting adjustments, as well as the problems related to the use of regional relations, such as the selection of a reference depth, the quantification of random variability and the strong-motion prediction. Moreover, a regional attenuation relationship specific for volcanic areas was also employed, allowing a more realistic evaluation of seismic hazard, as confirmed by the attenuation of macroseismic intensities.

Description: Published

Description: 295-316

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

Description: JCR Journal

Description: reserved