Rupture Kinematics and Structural‐Rheological Control of the 2016 M_w6.1 Amatrice (Central Italy) Earthquake From Joint Inversion of Seismic and Geodetic Data

Abstract

We investigate the rupture process of the 2016, Mw6.1 Amatrice earthquake, the first shock of a seismic sequence characterized by three damaging earthquakes occurred in central Italy between August and October. We jointly invert strong motion, High‐Rate GPS data, GPS, and DInSAR displacements and we adopt ad hoc velocity profiles of the crust below each station. The retrieved source model reveals a high degree of complexity, characterized by a prominent bilateral rupture with low slip at the hypocenter, two well‐separated slip patches and a rupture front accelerating when breaking the largest patch. The rupture of the main asperity features a slip‐velocity pulse that is impeded ahead of its current direction and splits into two pulses. In this fault section we find clues of structural and rheological control of the rupture propagation due to the fault system segmentation.

Half‐Graben Rupture Geometry of the 30 October 2016 MW6.6 Mt. Vettore‐Mt. Bove Earthquake, Central Italy

“…The authors define the OAST ramp as the downdip prolongation of the OAST trace. As they traced the structure, the 24 August 2016 Amatrice northern slip patch would have been confined not only laterally (toward the NW) by the thrust plane but also underneath it—as shown in Figure 4a of Pizzi et al () and Figures 5a and 5b of Cirella et al (). Nonetheless, this mismatches with the fact that according to the model of Cirella et al (), the rupture propagated up to the surface, where 5 km‐long surface faulting has been seen along the “Cordone del Vettore” splay (e.g., EMERGEO Working Group, ).…”

“…As they traced the structure, the 24 August 2016 Amatrice northern slip patch would have been confined not only laterally (toward the NW) by the thrust plane but also underneath it—as shown in Figure 4a of Pizzi et al () and Figures 5a and 5b of Cirella et al (). Nonetheless, this mismatches with the fact that according to the model of Cirella et al (), the rupture propagated up to the surface, where 5 km‐long surface faulting has been seen along the “Cordone del Vettore” splay (e.g., EMERGEO Working Group, ). The model of Cirella et al (), indeed, describes fault rupture that split into two propagating fronts as it hit the supposed OAST structural barrier, with one rupture front going downdip and a going updip, reaching unhindered the surface.…”

“…The OAST has been hypothesized by Pizzi et al () and Cirella et al () as a structural barrier that hindered propagation toward the NW of the 24 August 2016 rupture on the MVB fault. The authors define the OAST ramp as the downdip prolongation of the OAST trace.…”

“…A number of studies dealt with coseismic slip models for each of the three mainshocks of the 2016–2017 central Italy seismic sequence. All of them, made by inverting geodetic data (Cheloni et al, ; Huang et al, ; Lavecchia et al, ; Walters et al, ; Wang et al, ; Xu et al, ), seismological data (Chiaraluce et al, ; Papadopoulos et al, ; Pizzi et al, ; Tinti et al, ), or combinations of them (Cirella et al, ; Liu et al, ; Scognamiglio et al, ), described, at first order, the activation of a ~NW‐SE striking and SW dipping normal fault system. As for the 30 October M W 6.6 event, in particular, the models published to date (Cheloni et al, ; Chiaraluce et al, ; Liu et al, ; Papadopoulos et al, ; Pizzi et al, ; Scognamiglio et al, ; Walters et al, ; Wang et al, ; Xu et al, ) define an approximately N150°–160° striking normal fault, in agreement with the direction of active extension in this sector of the Apennines (e.g., Cheloni, Serpelloni, et al, ; D'Agostino, ; Devoti et al, ) and whose surface projection corresponds to the trace of the MVB fault system, along which surface faulting indeed occurred (Figure ; Civico et al, ; Galadini et al, ; Villani, Civico, et al, ).…”

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 Mw 6.2 Amatrice, Italy, Earthquake

“…Our inferred set of models of the 2016 Amatrice earthquake (including the best‐fitting model) agrees with published kinematic and dynamic models in a general sense. They exhibit bilateral rupture propagation and have two slip maxima away from the rupture nucleation (Aochi & Twardzik, ; Cirella et al, ; Pizzi et al, ). The latter feature has been also revealed in geodetic inversion by Huang et al ().…”