Slip Model for the 25 November 2016 Mw 6.6 Aketao Earthquake, Western China, Revealed by Sentinel-1 and ALOS-2 Observations

Abstract

Abstract:On 25 November 2016 (UTC 14:24:30), an Mw 6.6 dextral strike-slip earthquake ruptured Aketao county in the northwestern portion of the Kongur Shan extensional system, western China. We extracted surface deformation maps and investigated the distribution of the coseismic slip of the 2016 Aketao earthquake by exploiting the Interferometric Synthetic Aperture Radar data imaged by the Sentinel-1 satellites of the European Space Agency and the ALOS-2 satellite of the Japanese Aerospace Exploration Agency. Assuming the crust of the earth is an elastic half-space homogeneous medium, the best fitting slip model suggests a dip angle of 78 • for the seismogenic fault. The rupture of the 2016 Aketao earthquake may have consisted of two sub-events that occurred in rapid succession within a few seconds, resulting in two large discrete asperities with maximum slip of~0.85 m, which were separated by a~6 km-wide small slip gap. The maximum slip for the sub-event near the epicenter was mainly concentrated at a depth of~10 km and that of the other at a depth of~5 km. The estimated total seismic moment from the optimal slip model is 1.58 × 10 19 N·m, corresponding to an event with a moment magnitude of 6.74. More than 65% of the aftershocks occurred in the areas of increased Coulomb failure stress, in which the stress was estimated to have been increased by at least 0.1 bar. Matching the potential barrier on the fault with the depth distribution of aftershocks implies that friction on the causative fault was heterogeneous, which may play a primary role in controlling the active behavior of the Muji fault.

Cumulative and Coseismic (During the 2016 Mw6.6 Aketao Earthquake) Deformation of the Dextral‐Slip Muji Fault, Northeastern Pamir Orogen

“…Similar to the seismologic results, coseismic InSAR (Interferometric Synthetic Aperture Radar) observations determine a dextral-slip rupture on a steeply (~80°) south-dipping fault plane (e.g., Bie et al, 2018;Wang et al, 2017). The seismic rupture includes two slip patches that are separated by a slip gap of >5 km (Figure 6b).…”

Changes in Groundwater Level Possibly Encourage Shallow Earthquakes in Central Australia: The 2016 Petermann Ranges Earthquake

“…To account for the rupture complexities in the near-field, the size of the fault patches was set to be small (~200 m) near the surface and the fault model consists of 1,032 discrete triangular patches in total ( Figure 2g). We searched for the optimal uniform dip angle for which the root-mean-square (RMS) error reaches a minimum ( Figure S5b) (e.g., Wang et al, 2017). A nonnegative least squares inversion method and a scale-dependent umbrella Laplacian smoothing constraint were applied in the inversion (Maerten et al, 2005).…”

“…Red circles represent aftershocks from the ISC within 30 days after the main shock. Detailed InSAR data processing steps are described in the supporting information (Text S1; see also Berardino et al, 2002;Jónsson et al, 2002;Schmidt & Bürgmann, 2003;Wang et al, 2017). Red stars in the inset map represent the historical surface faulting earthquakes recorded in Petermann Ranges (Table S1; Clark & McPherson, 2013;Clark et al, 2014). acquisitions (Table S2).…”

“…In addition, we processed a pair of ascending ALOS-2 data acquired between 14 June 2016 and 28 November 2017 to obtain cumulative postseismic displacements from a second viewing geometry (Table S4). Detailed InSAR data processing steps are described in the supporting information (Text S1; see also Berardino et al, 2002;Jónsson et al, 2002;Schmidt & Bürgmann, 2003;Wang et al, 2017).…”

Source Parameters of the 2016–2017 Central Italy Earthquake Sequence from the Sentinel-1, ALOS-2 and GPS Data

“…With relatively short temporal and spatial baseline between SAR acquisitions, InSAR can reveal details of the near-to-far-field coseismic displacement, which is important in constraining source slip distribution, as well as assessing surface damage in a short period of time. It is very helpful for quick hazard responses and public access [4,[34][35][36]. In recent years, a new generation of SAR satellite missions has been proposed or launched, with the promise to boost our observational capability through reduced revisit times; we think quick hazard responses will be more publicly accessible through the remote sensing.…”