Kinematic finite fault and 3D seismic wave propagation of the 24 August, 2016, Mw 6.0 central Italy earthquake

Federica Magnoni Federica Magnoni,Emanuele Casarotti Emanuele Casarotti

doi:10.4401/ag-7265

Federica Magnoni Federica Magnoni, Emanuele Casarotti Emanuele Casarotti

Open Access

https://doi.org/10.4401/ag-7265

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Abstract

The magnitude Mw 6.0 earthquake of 24th August 2016 caused severe damages and nearly 300 fatalities in the central Italy region. Initial reports revealed an asymmetrical distribution of damage and coseismic effects, suggesting a major role of heterogeneities, both in the rupture history and in the geological structure of the region. Near realtime availability of seismological data afforded a timely determination of a finite fault model (Tinti et al., 2016). Here we test this source model by performing a 3D simulation of seismic wave propagation within a 3D structural model containing the major geological features of the region. Agreement between modeled seismograms and observed seismograms suggests that some complexities in the waveforms, such as high amplification in the region of the Mt. Vettore fault system, can be accounted for by complexities in the fault rupture and 3D structural models. Finally, the consistency of the hypothesis of two distinct events has been analyzed.

Highlights

The 24 August, 2016, Mw 6.0 central Italy earthquake occurred near the village of Accumoli with a strong impact in an area of complex geological structure
Additional improvements of the tomography and a new finite fault inversion with 3D velocity model are needed to better capture the pulses in the data at these frequencies, the amplitude of the signals is well constrained by the 3D simulations
The pattern of ground motion peak is strongly influenced by the inclusion of topography, with higher peaks in correspondece of higher reliefs

Summary

Introduction

The 24 August, 2016, Mw 6.0 central Italy earthquake occurred near the village of Accumoli with a strong impact in an area of complex geological structure. One of the primary assumptions in the procedure implemented by [Scognamiglio et al(2010)] is the adoption of 1D model that performs remarkably well in the central Italian region ([Magnoni et al(2014)], [Scognamiglio et al(2016)]). We probe this initial reliable finite fault solution with a forward simulation adopting a 3D velocity model ([Di Stefano & Ciaccio.(2014)]) that takes into account major geological features of the region. As in similar tests ([Magnoni et al(2014)], [Dreger et al(2015)]), for a 3D forward simulation we expect an incompatibility in adopting a seismic source solution obtained by inversion with 1D velocity models. A 3D approach is required in order to obtain a better understanding of the complexity that surprisingly appears in this relatively small event

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