Broadband Dynamic Rupture and Ground Motion Simulations (up to 5 Hz) of the 2016 Mw 6.2 Amatrice, Italy Earthquake

Broadband earthquake ground motion simulations (>1 Hz) are of great interest to seismologists and the earthquake engineering community. The evolution of the earthquake ruptures related to the 2016 Mw 6.2 Amatrice earthquake and the uniquely dense seismological recordings provide an opportunity to understand better the processes controlling earthquake dynamics, strong ground motion, and the relation between earthquakes. We here propose a novel approach to design data-driven broadband (up to 5 Hz) dynamic rupture scenarios from 0.5-1 Hz Bayesian dynamic finite-fault inversion (Gallovič et al., 2019). We analyze the effects of enhancing the best-fitting smooth dynamic source inversion result by subsequent adding of complexity such as non-planar fault geometry (i.e., fault listricity and surface roughness), topography, inelastic off-fault rheology, and visco-elastic attenuation. We utilize the open-source software package SeisSol (www.seissol.org), suited explicitly for incorporating such geometrical complexities and high-resolution simulations performed on modern supercomputers. The obtained scenarios reproduce synthetics resembling the observations in terms of velocity and accelerations waveforms and Fourier-amplitude-spectra (FAS) up to 5 Hz. The simulated peak ground velocity (PGV) maps show de-amplification of ground motion amplitudes on the foot-wall and amplification on the hanging-wall as a consequence of the wave-focusing effect caused by the listric fault curvature. This effect is seen mainly for distances up to 10 km from the fault. Our study suggests that the complexity of the earthquake source should not be neglected for the seismic hazard assessment for regions adjacent to active faults.