At the Istituto di Geodesia e Geofisica of the Università di Trieste a Very Broad Band (VBB) seis... more At the Istituto di Geodesia e Geofisica of the Università di Trieste a Very Broad Band (VBB) seismometer is operating. This instrument is part of the Intemational network MEDNET. [...]
To ensure environmental and public safety, critical facilities require rigorous seismic hazard an... more To ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor...
ABSTRACT Regional surface wave tomography is helpful in revealing the nature of the crust and the... more ABSTRACT Regional surface wave tomography is helpful in revealing the nature of the crust and the S-wave seismic velocity profiles beneath the sub-Antarctic Scotia Sea region. The seismic station coverage in this remote area is still poor, especially in the Scotia Sea and surrounding oceans. Seismic stations are located in Antarctic Peninsula, along the tip of South America, and in the islands along the North and South Scotia Ridges. Thus, it is not possible to apply the recently developed ambient noise seismic tomography for improving the spatial resolution of S-wave velocity models and earthquakes have to be used to infer crustal properties. The joint use of our regional network, global seismographic network stations and local temporary arrays provide better lateral resolution than that obtained in our previous studies (Vuan et al., 2000) concerning the Scotia Sea. Tomographic analysis is extended to new data, obtained using 15 broad band seismic stations and more than 300 regional events. Rayleigh and Love wave fundamental mode group velocities in the period range from 15 s to 50 s are considered (see Fig. 1). Errors in the measurements, estimated on clusters, are larger for Love waves than for Rayleigh waves and their averages are 0.060 km/s and 0.040 km/s, respectively. The correlation length of the heterogeneities, which can be resolved by Rayleigh waves, is generally lower than 100-150 km, but becomes greater near the periphery of the maps. The spatial resolution of Love waves is lower than 300 km, poorer than that of Rayleigh waves, due to the higher noise found in the horizontal components and resulting in a lighter path coverage. Models of the shear wave velocity in the crust and upper mantle for the tip of South America, the Falkland plateau, the Scotia Sea, the South Sandwich oceanic spreading ridge, the South Sandwich trench, the South Scotia ridge, the Antarctic Peninsula, the Bransfield Strait and the Drake Passage are presented. Moreover a database of 70 teleseismic earthquakes is used to infer the lithospheric structure beneath PMSA and ESPZ stations, deployed in Antarctic Peninsula respectively south of the intersection of the Hero Fracture Zone (HFZ) with the South Shetland Trench (SST), and at the extreme tip of the Antarctic Peninsula. The inversion of receiver function of teleseismic body waves is constrained by our group velocity tomographic study in the Scotia Sea region in order to minimize the non-uniqueness problem that results from the velocity-depth trade-off. The high noise level, typical of the oceanic environment, is overcome by stacking teleseisms with common receiver-station azimuthal angle and distance, and by selecting events with mb > 6.0 within a range of distances between 30° to 85°.
Bulletin of the Seismological Society of America, 2012
ABSTRACT The relevance of SmS seismic phase or multiple reflected SmS on the ground motion away f... more ABSTRACT The relevance of SmS seismic phase or multiple reflected SmS on the ground motion away from the earthquake source has been discussed in many studies during the past 30 years. The SmS and multiples are normally recognized by analyzing travel time arrivals on the basis of a priori well-known crustal models. Moho reflec-tions in borehole and surface accelerometric data of the KiK-net network for an inland Japanese earthquake are investigated. When reflected phases are transmitted effi-ciently, both amplitude and frequency content can be retrieved by using a simple time-frequency analysis of accelerometric records. For the 15 April 2007 M 5:4 Kinki crustal earthquake, Moho reflections are found at epicentral distances from 70 to 180 km. Borehole data show that SmS and multiples can be easily found in the fre-quency range from 0.25 to 2 s and in the group velocity window from 2:8 to 3:5 km=s. The coupling of borehole and surface stations of KiK-net data allows for the separate evaluation of the propagation effect along the source-receiver path and of the transfer function due to soft soils for these specific phases. An amplitude–period scaling re-lationship is found between the National Earthquake Hazards Reduction Program site classification and the observed transfer function for SmS phase and multiples. Online Material: Figures showing the effect of the source-time function duration on the multiple filter technique (MFT) diagrams, an MFT analysis of surface and borehole accelerograms, period–distance domain spectral amplitudes, and the average period–velocity transfer function for different NEHRP soil classes.
... 1), mirato a testare le potenzialità ed i costi del metodo.La sorgente utilizzata è un Miniba... more ... 1), mirato a testare le potenzialità ed i costi del metodo.La sorgente utilizzata è un Minibang-Isotta, e le sorgenti sono disposte lungo la congiungente i tre pozzi e in due ... Fig. 1 - Geometria delle sorgenti (asterischi rossi), dei ricevitori (triangoli azzurri) e dei pozzi (cerchi numerati ...
At the Istituto di Geodesia e Geofisica of the Università di Trieste a Very Broad Band (VBB) seis... more At the Istituto di Geodesia e Geofisica of the Università di Trieste a Very Broad Band (VBB) seismometer is operating. This instrument is part of the Intemational network MEDNET. [...]
To ensure environmental and public safety, critical facilities require rigorous seismic hazard an... more To ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor...
ABSTRACT Regional surface wave tomography is helpful in revealing the nature of the crust and the... more ABSTRACT Regional surface wave tomography is helpful in revealing the nature of the crust and the S-wave seismic velocity profiles beneath the sub-Antarctic Scotia Sea region. The seismic station coverage in this remote area is still poor, especially in the Scotia Sea and surrounding oceans. Seismic stations are located in Antarctic Peninsula, along the tip of South America, and in the islands along the North and South Scotia Ridges. Thus, it is not possible to apply the recently developed ambient noise seismic tomography for improving the spatial resolution of S-wave velocity models and earthquakes have to be used to infer crustal properties. The joint use of our regional network, global seismographic network stations and local temporary arrays provide better lateral resolution than that obtained in our previous studies (Vuan et al., 2000) concerning the Scotia Sea. Tomographic analysis is extended to new data, obtained using 15 broad band seismic stations and more than 300 regional events. Rayleigh and Love wave fundamental mode group velocities in the period range from 15 s to 50 s are considered (see Fig. 1). Errors in the measurements, estimated on clusters, are larger for Love waves than for Rayleigh waves and their averages are 0.060 km/s and 0.040 km/s, respectively. The correlation length of the heterogeneities, which can be resolved by Rayleigh waves, is generally lower than 100-150 km, but becomes greater near the periphery of the maps. The spatial resolution of Love waves is lower than 300 km, poorer than that of Rayleigh waves, due to the higher noise found in the horizontal components and resulting in a lighter path coverage. Models of the shear wave velocity in the crust and upper mantle for the tip of South America, the Falkland plateau, the Scotia Sea, the South Sandwich oceanic spreading ridge, the South Sandwich trench, the South Scotia ridge, the Antarctic Peninsula, the Bransfield Strait and the Drake Passage are presented. Moreover a database of 70 teleseismic earthquakes is used to infer the lithospheric structure beneath PMSA and ESPZ stations, deployed in Antarctic Peninsula respectively south of the intersection of the Hero Fracture Zone (HFZ) with the South Shetland Trench (SST), and at the extreme tip of the Antarctic Peninsula. The inversion of receiver function of teleseismic body waves is constrained by our group velocity tomographic study in the Scotia Sea region in order to minimize the non-uniqueness problem that results from the velocity-depth trade-off. The high noise level, typical of the oceanic environment, is overcome by stacking teleseisms with common receiver-station azimuthal angle and distance, and by selecting events with mb > 6.0 within a range of distances between 30° to 85°.
Bulletin of the Seismological Society of America, 2012
ABSTRACT The relevance of SmS seismic phase or multiple reflected SmS on the ground motion away f... more ABSTRACT The relevance of SmS seismic phase or multiple reflected SmS on the ground motion away from the earthquake source has been discussed in many studies during the past 30 years. The SmS and multiples are normally recognized by analyzing travel time arrivals on the basis of a priori well-known crustal models. Moho reflec-tions in borehole and surface accelerometric data of the KiK-net network for an inland Japanese earthquake are investigated. When reflected phases are transmitted effi-ciently, both amplitude and frequency content can be retrieved by using a simple time-frequency analysis of accelerometric records. For the 15 April 2007 M 5:4 Kinki crustal earthquake, Moho reflections are found at epicentral distances from 70 to 180 km. Borehole data show that SmS and multiples can be easily found in the fre-quency range from 0.25 to 2 s and in the group velocity window from 2:8 to 3:5 km=s. The coupling of borehole and surface stations of KiK-net data allows for the separate evaluation of the propagation effect along the source-receiver path and of the transfer function due to soft soils for these specific phases. An amplitude–period scaling re-lationship is found between the National Earthquake Hazards Reduction Program site classification and the observed transfer function for SmS phase and multiples. Online Material: Figures showing the effect of the source-time function duration on the multiple filter technique (MFT) diagrams, an MFT analysis of surface and borehole accelerograms, period–distance domain spectral amplitudes, and the average period–velocity transfer function for different NEHRP soil classes.
... 1), mirato a testare le potenzialità ed i costi del metodo.La sorgente utilizzata è un Miniba... more ... 1), mirato a testare le potenzialità ed i costi del metodo.La sorgente utilizzata è un Minibang-Isotta, e le sorgenti sono disposte lungo la congiungente i tre pozzi e in due ... Fig. 1 - Geometria delle sorgenti (asterischi rossi), dei ricevitori (triangoli azzurri) e dei pozzi (cerchi numerati ...
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Papers by A. Vuan