Deformation Related to an M 5 Earthquake Sequence on Xiangyang Lake-Burog Co Fault in Central Xizang, China, Observed by Sentinel-1 Data

摘要

Surface deformation associated with M 5 earthquakes is rarely observed. Using Sentinel-1 data collected from 2014 to 2017, we measured the surface deformation from a cluster of M 5 earthquakes occurring in August 2016 on the Xiangyang Lake-Burog Co fault in central Xizang, China, observing a maximum subsidence of similar to 1 cm in the satellite line-of-sight (LOS) direction over an similar to 8 x 10 km(2) area. We calculated the coseismic slip along the fault by applying an inversion to the geodetic dataset. The observed deformation is equivalent to the concentrated slip that could occur at depths of 4-12 km during one M-w similar to 5.2 earthquake and is comparable to the total slip that occurred during the earthquake sequence. We therefore propose that earthquakes in this sequence occurred in neighboring patches on the same fault plane and that the surface deformation we observed reflects the cumulative displacements caused by all earthquakes. However, we cannot rule out the possibility that the seismic sequence may have occurred at greater depth or in distributed areas and not displaced the surface but triggered an aseismic slip event, which has been observed in a few subduction zones and fast-slipping active faults.