Earthquake relocation using a 3D a-priori geological velocity model from the western Alps to Corsica: Implication for seismic hazard

Seismic Exploration of the Deep Structure and Seismogenic Faults in the Ligurian Sea by Joint Multi Channel and Ocean Bottom Seismic Acquisitions: Preliminary Results of the SEFASILS Cruise

“…First of all, the main seismic facies and morphostructural features imaged in both MCS SEFA13 and 14 profiles are correlated with those observed offshore the Ligurian Riviera and well documented e.g., [7][8][9][10][11]19,20] and references therein.…”

“…The tsunami polarity as well as the depth (10-12 km) and focal mechanisms of more recent local earthquakes all point to an active landward verging thrust fault beneath the margin, compatible with the tectonic uplift [2,3]. The northern half of the basin is also characterized by intraoceanic seismic activity, occasionally exceeding Mw6 ( Figure 1) and occurring along faults that are yet to be identified; focal depths range between 10 and 20 km [7]. The sedimentary cover in the deep basin is several km-thick and includes a thick, mobile, Messinian salt-bearing unit e.g., [8][9][10], whose surficial tectonic expression can interfere with motions of deeper origin ( Figure 2).…”

“…Raw OBS data were simply mixed with shot information from navigation data to produce standard OBS gathers after merging and sorting the two subsets corresponding to the two shot passes and applying minimum-phase bandpass filtering (Figure 4). After a careful binning of the MCS data using shot and receiver navigation files, the postcruise processing sequence, applied to both reflection profiles using CGG's Geovation ® software (version 6401) includes (1) field data transcription, (2) 2.5 Hz low-cut filter, (3) spherical divergence compensation, (4) noise attenuation in f-x domain, (5) trace editing, (6) cable and source corrections, (7) resampling from 2 to 4 ms, (8) first pass velocity picking, (9) multiple attenuation with 2D-SRME method (two passes) followed by Radon demultiple, (10) second pass velocity picking, (11) deconvolution, (12) third pass velocity picking, and (13) pre-stack Kirchhoff time migration. Prestack depth migration is also performed using a Ray+Born imaging technique [16], Common Image Gather analysis [17], as well as slope tomography being tested to build suitable velocity models for migration [18].…”

A 3D geological model of a structurally complex Alpine region as a basis for interdisciplinary research

“…Recently, the appreciation of their utility to several disciplines has grown, and software tools enabling their construction have proliferated 1 . In earth sciences and engineering, they have, inter alia , contributed to the development of improved earthquake location catalogues 2 and informed excavation and tunnelling projects 3 , 4 . They are also supporting ongoing radioactive waste storage site assessments 5 .…”

Assessment of earthquake locations in 3‐D deterministic velocity models: A case study from the Altotiberina Near Fault Observatory (Italy)

“…In some cases, controlled source seismic data are merged with passive tomographic models to constrain the structure of the main velocity discontinuities [e.g., Husen et al ., ; Wagner et al ., ]. In other studies, the seismic velocities from both commercial seismic lines and sonic logs [e.g., Cushing et al ., ] or from passive tomographic inversion [e.g., Bethoux et al ., ] are integrated into geological models to construct reliable velocity models. In Northern California, the geological model of the San Francisco Bay area has been converted into seismic velocities by merging data from vertical seismic profiles (VSPs), sonic logs in boreholes, active and passive seismic studies, and laboratory measurements [ Brocher , ].…”