Development and Testing of a 3D Seismic Velocity Model of the Po Plain Sedimentary Basin, Italy

Abstract

We built a 3D seismic model of the Po Plain and neighboring regions of northern Italy, covering altogether an area about 600 km by 300 km with an approximately 1 km spaced grid. We started by collecting an extensive and diverse set of geological and geophysical data, including seismic reflection and refraction profiles, borehole logs, and available geological information. Major geological boundaries and discontinuities have thus been identified and mapped into the model. We used kriging to interpolate the geographically sparse information into continuous surfaces delimiting geological bodies with laterally varying thickness. Seismic-wave properties have been assigned to each unit using a rule-based system and, V P , V S , and ρ derived from other studies. Sedimentary strata, although with varying levels of compaction and hence material properties, may locally reach a thickness of 15 km and give rise to significant effects in seismic-wave propagation. We have used our new model to compute the seismic response for two recent earthquakes, to test its performance. Results show that the 3D model reproduces the large amplitude and the long duration of shaking seen in the observed waveforms recorded on sediments, whereas paths outside the basin may be well fit by more homogeneous (1D) hard rock structure. We conclude that the new model is suited for simulation of wave propagation, mostly for T > 3 s, and may serve well as a constraint for earthquake location and further improvements via body-or surface-wave inversion.

Italian and Alpine three‐dimensional crustal structure imaged by ambient‐noise surface‐wave dispersion

“… MAMBo model [ Molinari et al ., ] in the Po basin, EPcrust velocity range in the crust and EPmantle in the mantle.…”

“…Owing to the mentioned difficulties in crustal imaging, a number of fundamental questions are still open concerning orogeny and mantle dynamics in this complex area [ Faccenna and Becker , ]. Local‐scale crustal models have been derived from geological data sets [ Molinari et al ., ], active reflection and refraction seismic experiments [e.g., Waldhauser et al ., ; Brückl et al ., ], P‐wave travel‐time tomography [e.g., Chiarabba and Amato , ; Piromallo and Morelli , ; Serretti and Morelli , ; Gualtieri et al ., ], local earthquake tomography (LET) [e.g., Diehl et al ., ; Di Stefano et al ., ], receiver‐function studies [e.g., Piana Agostinetti and Amato , ], and combinations of the latter two data types [ Wagner et al ., ; Spada et al ., ]. These methods provide important constraints on three‐dimensional (3‐D) P‐wave velocity structure and on the depth of sharp discontinuities.…”

“…These data have strong sensitivity to crustal v S structure, but weak sensitivity to discontinuities and their depth. The geometry of crustal seismic discontinuities under Italy and the Alps, however, has been determined in a number of studies using other observation techniques: model EPcrust [Molinari and Morelli, 2011] includes robust interface geometry determinations based on seismic reflection and refraction studies; Spada et al [2013] have constrained Moho depth via controlled-source seismology, local earthquake tomography and receiverfunction analysis; the 3-D structure and depth of the deep Po-plain sedimentary basin has been determined from geological data [Molinari et al, 2015].…”

Bayesian rupture imaging in a complex medium: The 29 May 2012 Emilia, Northern Italy, earthquake

“…The strong motion analysis shows that near-source records are particularly complex, characterized by a mix of body waves and strong surface waves [Luzi et al, 2013;Cultrera et al, 2014;Dujardin et al, 2016]. This arises because the quaternary deposits of the Po Plain covering the seismic fault of the M w 6.0 shock are spatially variable, with a thickness ranging from about 200 m to 2 km [Paolucci et al, 2015;Molinari et al, 2015]. In addition, site effects studies report amplification peaks down to very low frequencies (peaks at 0.15 and 0.7 Hz) [Milana et al, 2014].…”

Algorithms for CO2 Storage Capacity Estimation: Review and Case Study

“…The published interpretations of Po Plain structural setting as well as the available underground datasets [50,53,[61][62][63][64] were reviewed in order to check the reconstructions of Pliocene base surface and the sedimentary sequence above it. The Pliocene base surface defines the reservoir bottom in these areas, which is constituted by the Porto Corsini, the Porto Garibaldi and minorly the Asti formations [51] (Fig.…”