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  • 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
  • American Geophysical Union  (25)
  • Elsevier  (17)
  • Public Library of Science
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  • 1
    Publication Date: 2021-06-21
    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
    Keywords: Earthquake early-warning ; Real-time seismology ; Bayesian analysis ; Missed and false alarm ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-05-12
    Description: Today, satellite remote sensing has reached a key role in Earth Sciences. In particular, Synthetic ApertureRadar (SAR) sensors and SAR Interferometry (InSAR) techniques are widely used for the study of dynamicprocesses occurring inside our living planet. Over the past 3 decades, InSAR has been applied for mappingtopography and deformation at the Earth’s surface. These maps are widely used in tectonics, seismology,geomorphology, and volcanology, in order to investigate the kinematics and dynamics of crustal faulting,the causes of postseismic and interseismic displacements, the dynamics of gravity driven slope failures,and the deformation associated with subsurface movement of water, hydrocarbons or magmatic fluids.
    Description: Published
    Description: 58-82
    Description: 1T. Geodinamica e interno della Terra
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: reserved
    Keywords: SAR ; InSAR ; Earth observation ; Surface displacements ; Satellite missions ; Advanced InSAR ; Earthquake studies ; Volcanic studies ; Tectonic process ; Coseismic studies ; Soil liquefaction ; Post-seismic studies ; Interseismic studies ; Volcanic unrest ; Pre-eruptive phase ; Eruptive phase ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2020-09-29
    Description: This chapter summarizes a comparative study of shear-wave velocity models and seismic sources in the Campanian volcanic areas of Vesuvius and Phlegraean Fields. These velocity models were obtained through the nonlinear inversion of surfacewave tomography data, using as a priori constraints the relevant information available in the literature. Local group velocity data were obtained by means of the frequency–time analysis for the time period between 0.3 and 2 s and were combined with the group velocity data for the time period between 10 and 35 s from the regional events located in the Italian peninsula and bordering areas and two station phase velocity data corresponding to the time period between 25 and 100 s. In order to invert Rayleigh wave dispersion curves, we applied the nonlinear inversion method called hedgehog and retrieved average models for the first 30–35km of the lithosphere, with the lower part of the upper mantle being kept fixed on the basis of existing regional models. A feature that is common to the two volcanic areas is a low shear velocity layer which is centered at the depth of about 10 km, while on the outside of the cone and along a path in the northeastern part of the Vesuvius area this layer is absent. This low velocity can be associated with the presence of partial melting and, therefore, may represent a quite diffused crustal magma reservoir which is fed by a deeper one that is regional in character and located in the uppermost mantle. The study of seismic source in terms of the moment tensor is suitable for an investigation of physical processes within a volcano; indeed, its components, double couple, compensated linear vector dipole, and volumetric, can be related to the movements of magma and fluids within the volcanic system. Although for many recent earthquake events the percentage of double couple component is high, our results also show the presence of significant non-double couple components in both volcanic areas.
    Description: Published
    Description: 287-309
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
    Format: 8247786 bytes
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  • 4
    Publication Date: 2017-04-04
    Description: Strong electrical signals that correspond to the Mw = 9.3 earthquake of 26 December 2004, which occurred at 0058:50.7 UTC off the west coast of northern Sumatra, Indonesia, were recorded by an electrostatic sensor (a device that detects short-term variations in Earth’s electrostatic fi eld) at a seismic station in Italy, which had been installed to study the infl uence of local earthquakes on a new landslide monitoring system. Electrical signals arrived at the station practically instantaneously and were detected up to several hours before the onset of the Sumatra earthquake (Figure 1) as well as before local quakes. The corresponding seismic signals (p-waves) arrived 740 seconds after the start of the earthquake. Because the electrical signals travel at the speed of light, electrical monitoring for the global detection of very strong earthquakes could be an important tool in signifi cantly increasing the hazard alert window.
    Description: Published
    Description: 445-460
    Description: open
    Keywords: Sumatra earthquake ; electrostatic signals ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2017-04-04
    Description: We estimated the source parameters of 53 local earthquakes (2.0 〈ML 〈 5.7) of the Friuli-Venezia Giulia (Northeastern Italy) area, recorded by the short-period local seismic network of the Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS), in the period 1995–2003. Data were selected on the basis of high quality locations and focal mechanisms. Standard H/V spectral ratios (HVRS) of the three-component stations of the network were performed in order to assess local amplifications, and only stations showing HVRS not exceeding two were considered for the source parameters estimation. Both velocity and acceleration data were used to compute the SH-wave spectra. Observed spectra were corrected for attenuation effects using an independent regional estimate of the quality factor Q and a station dependent estimate of the spectral decay parameter k. Only earthquakes withML 〉 3.0 recorded with a sampling rate of 125 cps were used to compute k, thus allowing to visualize a linear trend of the high frequency acceleration spectrum up to 40–50 Hz. SH-wave spectra, corrected for attenuation, showed an ω−2 shape allowing a good fit with the Brune model. Seismic moments and Brune radii ranged between 1.5 × 1012 and 1.1 × 1017 Nm and between 0.1 and 2.7 km respectively.We obtainedMo = 1.1 × 1017 Nm for the seismic moment of the Kobarid (SLO) main shock, in good agreement with the Harvard CMT solution (Mo = 3.5 × 1017 Nm). Brune stress drops were confined to the range from 0.07 to 5.31MPa, with an average value of 0.73MPa and seem to be approximately constant over five orders of magnitude of seismic moment. Radiated seismic energy computed from two nearby stations scales with seismic moment according to logEs = 1.30 logMo − 9.06, and apparent stress values are between 0.02 and 4.26MPa. The observed scatter of Brune stress drop data allowed to hypothesize a scaling relation Mo ∝ f −3.43 c between seismic moment and corner frequency in order to accommodate both Brune stress drop and apparent stress scalings. No systematic differences are evidenced between stress parameters of earthquakes with different focal mechanisms. As a consequence, a relation of the seismic stress release with the strength of rocks can be hypothesized. A high correlation (r 〉 0.9) of Brune stress drop is found with both apparent stress and RMS stress drop, according to σB = 2.0 σa and σrms = 2.26 σB respectively.
    Description: Published
    Description: 148-167
    Description: JCR Journal
    Description: reserved
    Keywords: Earthquakes ; Attenuation ; Seismic spectra ; Seismic moment ; Seismic stress ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: The inner regions of the Antarctic continent are generally regarded as nearly aseismic, although microseismicity is known to occur beneath some outlet ice streams, related to the interaction between the fast flowing ice and the bedrock. Here we show the occurrence of unusual earthquakes beneath an Antarctic outlet glacier that share almost the same magnitude, pointing to the repeated rupture of a single asperity. These seismic events produce waveforms with very high similarity and uncommon spectrum and are tightly clustered in space but, unlike other reported instances of repeating earthquakes on a patch of the San Andreas Fault, they occur in frequent irregular swarms. Evidence locates these events at the rock–ice interface under the glacier, and shows the existence of stick–slip motion on a smaller scale than the large slow slip events detected by global seismographs. Seismic behaviour of large glaciers can presumably be connected to surges in ice motion. This study determines a little known environment for fracture dynamics studies, while also contributing to the understanding of the coupling processes between fast flowing glaciers and bedrock that influence ice stream evolution and stability.
    Description: Progetto Nazionale di Ricerca in Antartide (PNRA) Antarctica New Zealand (ANZ)
    Description: Published
    Description: 151–158
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Glacial earthquakes ; Glacial dynamics ; Gutenberg-Richter relationship ; Double-difference hypocentre location ; Repeating earthquake ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: We calculated the impact on Southern Italy of a large set of tsunamis resulting from earthquakes generated by major fault zones of the Mediterranean Sea. Our approach merges updated knowledge on the regional tectonic setting and scenario-like calculations of expected tsunami impact. We selected three potential source zones located at short, intermediate and large distance from our target coastlines: the Southern Tyrrhenian thrust belt; the Tell-Atlas thrust belt; and the western Hellenic Arc. For each zone we determined a Maximum Credible Earthquake and described the geometry, kinematics and size of its associated Typical Fault. We then let the Typical Fault float along strike of its parent source zone and simulated all tsunamis it could trigger. Simulations are based on the solution of the nonlinear shallow water equations through a finite-difference technique. For each run we calculated the wave fields at desired simulation times and the maximum water elevation field, then produced travel-time maps and maximum wave-height profiles along the target coastlines. The results show a highly variable impact for tsunamis generated by the different source zones. For example, a large Hellenic Arc earthquake will produce a much higher tsunami wave (up to 5 m) than those of the other two source zones (up to 1.5 m). This implies that tsunami scenarios for Mediterranean Sea countries must necessarily be computed at the scale of the entire basin. Our work represents a pilot study for constructing a basin-wide tsunami scenario database to be used for tsunami hazard assessment and early warning.
    Description: Italian Civil Defense; Project “Development of new technologies for the protection of the Italian territory from natural hazards” funded by the Italian Ministry of University and Research
    Description: Published
    Description: B01301
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: JCR Journal
    Description: partially_open
    Keywords: Tsunamis ; Mediterranean Sea ; Seismotectonics ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2017-04-04
    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
    Keywords: Seismotectonics ; Seismic source zone model ; Seismic hazard ; Italy ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: In this study, we compute the effect of stress change due to previous historical earthquakes on the probability of occurrence of future earthquakes on neighboring faults. Following a methodology developed in the last decade, we start from the estimate of the probability of occurrence in the next 50 years for a characteristic earthquake on known seismogenic structures, based on a time-dependent renewal model. Then a physical model for the Coulomb stress change caused by previous earthquakes on these structures is applied. The influence of this stress change on the occurrence rate of characteristic earthquakes is computed, taking into account both permanent (clock advance) and temporary (rate-and-state) perturbations. We apply this method to the computation of earthquake hazard of the main seismogenic structures recognized in the Central and Southern Apennines region, for which both historical and paleoseismological data are available. This study provides the opportunity of reviewing the problems connected with the estimate of the parameters of a renewal model in case of characteristic earthquakes characterized by return times longer than the time spanned by the available catalogues and the applicability of the concept of characteristic earthquake itself. The results show that the estimated effect of earthquake interaction in this region is small compared with the uncertainties affecting the statistical model used for the basic time-dependent hazard assessment.
    Description: Published
    Description: B08313
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Stress interaction, occurrence probability, characteristic earthquakes ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: We (re)analyzed the source of the 26 December 2004 Sumatra-Andaman earthquake and tsunami through a nonlinear joint inversion of an in-homogeneous dataset made up of tide-gages, satellite altimetry, and far-field GPS recordings. The purpose is two-fold: (1) the retrieval of the main kinematics rupture parameters (slip, rake, rupture velocity); (2) the inference of the rigidity of the source zone. We independently estimate the slip from tsunami data and the seismic moment from geodetic data, so to derive the rigidity. Our results confirm that the source of the 2004 Sumatra-Andaman earthquake has a complex geometry, constituted by three main slip patches, with slip peaking at ~30 meters in the Southern part of the source. The rake direction rotates counter-clockwise at North, according to the direction of convergence along the trench. The rupture velocity is higher in the deeper than in the shallower part of the source, consistently with the expected increase of rigidity with depth. It is also lower in the Northern part, consistently with known variations of the incoming plate properties and shear velocity. Our model features a rigidity (20-30 GPa), that is lower than PREM average for the seismogenic volume [Dziewonski and Anderson, 1981]. The source rigidity is one of the factors controlling the tsunamigenesis: for a given seismic moment, the lower the rigidity, the higher the induced seafloor displacement. The general consistence between our source model and previous studies supports the effectiveness of our approach to the joint inversion of geodetic and tsunami data for the rigidity estimation.
    Description: In press
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: Source process ; Sumatra ; Tsunami ; joint inversion ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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