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  • 1
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    Moho Reflection Effects in the Po Plain (Northern Italy) Observed from Instrumental and Intensity Data (2011)
    Seismological Society of America (SSA)
    Details
    Publication Date: 2011-10-01
    Description: Recent moderate-sized earthquakes (ML[≤]5.2) that occurred in northern Italy demonstrate that the currently available ground-motion prediction equations (GMPEs) largely underestimate shaking in the Po Plain region at hypocentral distances greater than 70 km. In order to investigate this phenomenon, we collected a set of peak ground acceleration (PGA) observations for weak and moderate earthquakes in the area. Nonparametric regression analysis of PGA observations as a function of magnitude and hypocentral distance shows that PGA is systematically enhanced for distances between 70 and 200 km. An indirect estimation through the analysis of the attenuation of macroseismic intensities suggests that the effect also applies to strong earthquakes (ML〉5.5). We performed numerical modeling experiments to investigate the cause of the phenomenon. The characteristics of the computed synthetic seismograms indicate that the enhancement of ground motion is mainly an effect of the reflection of S waves at the Moho (SmS phase). The analysis of both real and synthetic data shows that the Moho reflection effect is maximized at hypocentral distances between 90 and 150 km, where the PGA increases by a factor larger than 2.4.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America (SSA)
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  • 2
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    Ground-motion simulations within ShakeMap methodology: application to the 2008 Iwate-Miyagi Nairiku (Japan) and 1980 Irpinia (Italy) earthquakes (2013)
    Oxford University Press
    Details
    Publication Date: 2013-03-12
    Description: ShakeMap package uses empirical ground motion prediction equations (GMPEs) to estimate the ground motion where recorded data are not available. The GMPEs, however, account only for average characteristics of source and wave propagation processes and the ground motion estimate can fail in the near-source area when few stations are available. In this study, we investigate the performance of ShakeMap in the near-fault area when source effects are included at different levels of complexity. We focus on the 2008, M w 7.0, Iwate-Miyagi Nairiku (Japan) earthquake because of the large amount of recording stations which contribute to the definition of a reference shakemap. After shutting off some stations from the original data set, we evaluate the resulting shakemaps bias as if the earthquake was recorded at a smaller number of receivers. We then compute the shakemaps replacing the missing records with synthetic seismograms from a hybrid deterministic-stochastic method for extended fault. We suppose an increasing knowledge of seismic source approximation and of the slip history on the fault, obtained both from the expeditious inversion of teleseismic data and, afterwards, from strong-motion data inversion. In particular, a non-linear kinematic inversion technique allowed us to retrieve a complete kinematic description of the source process on the fault plane. Our results reveal that the integration of real data with synthetics is quite efficient, providing reliable shaking maps mainly when near source recordings are scarce. However, the accuracy of the fault plane position plays a major role in increasing the effectiveness of the results. We then apply the methodology to a poorly instrumented earthquake of similar magnitude, the 1980, M s 6.9, Irpinia (Southern Italy) earthquake. When the peak motions inferred from synthetic seismograms are included in the database, the fit with respect to the observed Mercalli–Cancani–Sieberg intensities improves.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 3
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    The dynamics of the 2001 Etna eruption as seen by full moment tensor analysis (2010)
    Oxford University Press
    Details
    Publication Date: 2010-03-01
    Description: The Mt. Etna eruption of July 2001 was announced by severe seismic activity and by the opening of a 7-km-long zone of densely distributed fractures. The large amount of data collected gave a unique opportunity to study the magma migration process and to infer the position and geometry of the uprising dyke. Results from multidisciplinary approaches suggest that the observed phenomenology was the result of the rapid intrusion of a vertical dyke, oriented roughly N–S and located a few km south of the summit region. To add new constraints to the dynamics of the eruption process, in this study we determine the full seismic moment tensors of 61 earthquakes, selected among those occurring between July 12 and July 18 (Md≥ 2.2), located in a depth ranging from 1 km above sea level (a.s.l.) to 3 km below sea level (b.s.l.). At the beginning of the seismic swarm, the dominant component of the seismic source tensor is double-couple percentage (around 65 per cent on average) statistical significant at 95 per cent confidence level and in the following hours the non-double-couple components increase at the expenses of the double-couple. Such observations are related well with the system of fractures formed just before the eruption, whereas the increasing non-double-couple components can be explained as the response of the confining rocks to the rising magma and degassing processes. The type of focal mechanisms retrieved are predominantly of normal fault type (44 per cent), strike slip (30 per cent) and thrust mechanisms (9 per cent), and outline a scenario that concurs with the stress regime induced by a dyke injection. The space–time analysis of seismic source locations and source moment tensors (1) confirms the evidence of a vertical dyke emplacement that fed the 2001 lateral eruption and (2) adds new insights to support the hypothesis of the injection of a second aborted dyke, 2 km SE from the fractures zone.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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  • 4
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    Ground-motion simulations within ShakeMap methodology: application to the 2008 Iwate-Miyagi Nairiku (Japan) and 1980 Irpinia (Italy) earthquakes (2013)
    Oxford University Press
    Details
    Publication Date: 2013-01-16
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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  • 5
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    Moho Reflection Effects in the Po Plain (Northern Italy) Observed from Instrumental and Intensity Data (2011)
    Seismological Society of America
    Details
    Publication Date: 2011-09-26
    Description: Recent moderate-sized earthquakes (M (sub L) 〈 or = 5.2) that occurred in northern Italy demonstrate that the currently available ground-motion prediction equations (GMPEs) largely underestimate shaking in the Po Plain region at hypocentral distances greater than 70 km. In order to investigate this phenomenon, we collected a set of peak ground acceleration (PGA) observations for weak and moderate earthquakes in the area. Nonparametric regression analysis of PGA observations as a function of magnitude and hypocentral distance shows that PGA is systematically enhanced for distances between 70 and 200 km. An indirect estimation through the analysis of the attenuation of macroseismic intensities suggests that the effect also applies to strong earthquakes (M (sub L) 〉 5.5). We performed numerical modeling experiments to investigate the cause of the phenomenon. The characteristics of the computed synthetic seismograms indicate that the enhancement of ground motion is mainly an effect of the reflection of S waves at the Moho (SmS phase). The analysis of both real and synthetic data shows that the Moho reflection effect is maximized at hypocentral distances between 90 and 150 km, where the PGA increases by a factor larger than 2.4.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America
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  • 6
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    OGS improvements in the year 2011 in running the Northeastern Italy Seismic Network (2013)
    Copernicus
    Details
    Publication Date: 2013-04-30
    Description: The Centro di Ricerche Sismologiche (CRS, Seismological Research Center) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS (Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude Mw = 6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the Northeastern Italy Seismic Network: it currently consists of 12 very sensitive broad band and 21 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data centre in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of 93 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of Northeastern Italy, as shown in Fig. 1 (Bragato et al., 2011; Saraò et al., 2010). Since 2002 OGS-CRS is using the Antelope software suite as the main tool for collecting, analyzing, archiving and exchanging seismic data, initially in the framework of the EU Interreg IIIA project "Trans-national seismological networks in the South-Eastern Alps" (Bragato et al., 2010; Pesaresi et al., 2008). SeisComP is also used as a real time data exchange server tool. In order to improve the seismological monitoring of the Northeastern Italy area, at OGS-CRS we tuned existing programs and created ad hoc ones like: a customized web server named PickServer to manually relocate earthquakes, a script for automatic moment tensor determination, scripts for web publishing of earthquake parametric data, waveforms, state of health parameters and shaking maps, noise characterization by means of automatic spectra analysis, and last but not least scripts for email/SMS/fax alerting. A new OGS-CRS real time seismological website (http://rts.crs.inogs.it/) has also been operative since several years.
    Print ISSN: 1680-7340
    Electronic ISSN: 1680-7359
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 7
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    Data mining from Antelope at OGS-CRS (Udine, Italy) (2010)
    CTBTO
    Details
    Publication Date: 2017-04-04
    Description: Since 2002 the Seismological Research Centre (Centro di Ricerche Sismologiche, CRS, http://www.crs.inogs.it) of the National Institute for Oceanography and Experimental Geophysics (OGS) in Trieste (Italy) is involved in the EU INTERREG IIIA project “Trans-national seismological networks in the South-Eastern Alps” together with other four Institutions: Zentralanstalt für Meteorologie und Geodynamik (ZAMG) in Vienna (Austria), the Earth Science Department of the Trieste University in Trieste (Italy) and the Agencija Republike Slovenije Za Okolje (ARSO) in Ljubljana (Slovenia). The commercial Antelope software suite from BRTT has been chosen as the common basis for real time data exchange, rapid location of earthquakes and alerting. Antelope is a powerful software suite that easily allows sharing data in real time among neighbouring institutions. However it must be tuned to each seismological data centre needs in order to extract the specific information required. At OGS-CRS we adapted existing programs and created new ones like: a customized interface to manually relocate earthquakes, a script for automatic moment tensor determination, scripts for web publishing of earthquake locations, waveforms, state of health parameters and shaking maps, plus scripts for email/SMS/fax alerting.
    Description: Published
    Description: Vienna, Austria
    Description: 5.2. TTC - Banche dati di sismologia strumentale
    Description: open
    Keywords: data mining ; Antelope ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 8
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    The dynamics of the 2001 Etna eruption as seen by full moment tensor analysis (2011)
    Wiley - Blackwell; Royal Astronomical Society
    Details
    Publication Date: 2017-04-04
    Description: The Mt. Etna eruption of July 2001 was announced by severe seismic activity and by the opening of a 7-km-long zone of densely distributed fractures. The large amount of data collected gave a unique opportunity to study the magma migration process and to infer the position and geometry of the uprising dyke. Results from multidisciplinary approaches suggest that the observed phenomenology was the result of the rapid intrusion of a vertical dyke, oriented roughly N–S and located a few km south of the summit region. To add new constraints to the dynamics of the eruption process, in this study we determine the full seismic moment tensors of 61 earthquakes, selected among those occurring between July 12 and July 18 (Md ≥ 2.2), located in a depth ranging from 1 km above sea level (a.s.l.) to 3 km below sea level (b.s.l.). At the beginning of the seismic swarm, the dominant component of the seismic source tensor is double-couple percentage (around 65 per cent on average) statistical significant at 95 per cent confidence level and in the following hours the non-double-couple components increase at the expenses of the double-couple. Such observations are related well with the system of fractures formed just before the eruption, whereas the increasing non-double-couple components can be explained as the response of the confining rocks to the rising magma and degassing processes. The type of focal mechanisms retrieved are predominantly of normal fault type (44 per cent), strike slip (30 per cent) and thrust mechanisms (9 per cent), and outline a scenario that concurs with the stress regime induced by a dyke injection. The space–time analysis of seismic source locations and source moment tensors (1) confirms the evidence of a vertical dyke emplacement that fed the 2001 lateral eruption and (2) adds new insights to support the hypothesis of the injection of a second aborted dyke, 2 km SE from the fractures zone.
    Description: Published
    Description: 951–965
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Time series analysis ; Earthquake source observations ; Volcano seismology ; Eruption mechanisms and flow emplacement ; Volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Moho reflection effects in the Po plain (Northern Italy) observed from instrumental and intensity data. (2012)
    Details
    Publication Date: 2017-04-04
    Description: Recent moderate-sized earthquakes (ML≤5.2) that occurred in northern Italy demonstrate that the currently available ground-motion prediction equations (GMPEs) largely underestimate shaking in the Po Plain region at hypocentral distances greater than 70 km. In order to investigate this phenomenon, we collected a set of peak ground acceleration (PGA) observations for weak and moderate earthquakes in the area. Nonparametric regression analysis of PGA observations as a function of magnitude and hypocentral distance shows that PGA is systematically enhanced for distances between 70 and 200 km. An indirect estimation through the analysis of the attenuation of macroseismic intensities suggests that the effect also applies to strong earthquakes (ML〉5.5). We performed numerical modeling experiments to investigate the cause of the phenomenon. The characteristics of the computed synthetic seismograms indicate that the enhancement of ground motion is mainly an effect of the reflection of S waves at the Moho (SmS phase). The analysis of both real and synthetic data shows that the Moho reflection effect is maximized at hypocentral distances between 90 and 150 km, where the PGA increases by a factor larger than 2.4.
    Description: Published
    Description: 2142-2152
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: restricted
    Keywords: moho ; reflection ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
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    Acquiring, archiving, analyzing and exchanging seismic data in real time at the Seismological Research Center of the OGS in Italy (2012)
    Istituto Nazionale di Geofisica e Vulcanologia
    Details
    Publication Date: 2017-04-04
    Description: After the 1976 Friuli earthquake (Ms = 6.5) in north-eastern Italy that caused about 1,000 casualties and widespread destruction in the Friuli area, the Italian government established the Centro di Ricerche Sismologiche (CRS). This is now a department of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), and it is specifically devoted to the monitoring of the seismicity of north-eastern Italy. Since its inception, the North-East Italy Seismic Network has grown enormously. Currently, it consists of 14 broad-band and 20 short-period seismic stations, all of which are telemetered to and acquired in real time at the OGS-CRS data center in Udine. Data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of 94 seismic stations acquired in real time, which confirms that the OGS is the reference institute for seismic monitoring of north-eastern Italy. Since 2002, CRS has been using the Antelope software suite as the main tool for collecting, analyzing, archiving and exchanging seismic data. SeisComP is also used as a real-time data exchange server tool. A customized web accessible server is used to manually relocate earthquakes, and automatic procedures have been set-up for moment-tensor determination, shaking-map computation, web publishing of earthquake parametric data, waveform drumplots, state-of-health parameters, and quality checks of the station by spectra analysis. Scripts for email/SMS/fax alerting to public institutions have also been customized. Recently, a real-time seismology website was designed and set-up (http://rts.crs.inogs.it/).
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Published
    Description: 67-75
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Seismological Research Center ; OGS ; acquiring seismic data ; archiving seismic data ; analyzing seismic data ; exchanging seismic data ; real time ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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