Tomographic Images of the 2016 Central Italy M6.5 and M6.1 Normal Faults by Massive Local Earthquakes Tomography

Session: Seismic Imaging of Fault Zones
Type: Oral
Date: 4/29/2020
Time: 02:45 PM
Room: 215 + 220
Description: 

The distribution of aftershocks and local earthquake tomography give robust images of faults at depths that are directly un-accessible. Since many decades, LET contributed in the definition of the crustal structure for many faults, but the current capability to record and handle massive set of data during seismic sequences opens the scene to high resolution imaging of faults and the necessity to develop more sophisticated procedures. Our focus is on the fault system where the 2016 Central Italy earthquake sequence developed, with two large normal faulting earthquakes originated on close and partially overlapping segments. We present a high detail, high resolution Vp and Vp/Vs image of the fault, obtained with standard procedure but for the first time using about 50.000 aftershocks. The relocation of more than 260 k-earthquakes with this model yields accurate definition of fault geometry and reveals the general architecture of the system and pre-existing structures.

Material properties changes along the fault account for a different rheological behavior during the seismic sequence. We observe that aftershocks tend to occur around high Vp/Vs patches, where large coseismic slip concentrated. Mainshocks break fault portions that, although limited and segmented by inherited structural complexity, are interfering during the same faulting episode.

As a general inference, the huge space/time sampling of data extracted for the sequence opens the possibility to develop ad hoc studies of fault processes at a very high resolution scale.

Presenting Author: Claudio Chiarabba

Authors