Imaging of Seismogenic Asperities of the 2016 ML 6.0 Amatrice, Central Italy, Earthquake Through Dynamic Rupture Simulations

Abstract

Numerical simulations are carried out for the dynamic rupture and wave propagation process of the 24th August 2016 ML 6.0 Amatrice, Italy, earthquake, using a boundary domain method (BDM), a hybrid method of boundary integral equation and finite difference methods. Dynamic rupture parameters of two seismogenic asperities are searched by iterative search through the comparison of the near-field ground motions. The preferred models indicate two asperities, aligned at around 4–5 km depth and separated from each other as well as from the initial rupture point. This requires a few supplementary patches connecting them, and that are less energetic than the asperities. The asperities are characterized by a radius of 2–3 km in the south (first to rupture) and of 2–4 km in the north (second to rupture), and the corresponding fracture energies of the asperities are (25.35 ± 0.63) × 1012 J and (38.05 ± 7.91) × 1012 J, respectively. These values are consistent with the scaling relation extrapolated from various analyses of large earthquakes. Although the parameter space of the search is limited due to the numerical performance of the dynamic rupture simulation, the proposed simple characterization of the earthquakes source confirms the scaling relation in fracture energy of the seismogenic asperities, which is essential for constructing mechanical earthquake source models.