Post-seismic deformation mechanism of the July 2015 MW 6.5 Pishan earthquake revealed by Sentinel-1A InSAR observation

Abstract

On 3 July 2015, the Mw 6.5 Pishan earthquake occurred at the junction of the southwestern margin of the Tarim Basin and the northwestern margin of the Tibetan Plateau. To understand the seismogenic mechanism and the post-seismic deformation behavior, we investigated the characteristics of the post-seismic deformation fields in the seismic area, using 9 Sentinel-1A TOPS synthetic aperture radar (SAR) images acquired from 18 July 2015 to 22 September 2016 with the Small Baseline Subset Interferometric SAR (SBAS-InSAR) technique. Postseismic LOS deformation displayed logarithmic behavior, and the temporal evolution of the post-seismic deformation is consistent with the aftershock sequence. The main driving mechanism of near-field post-seismic displacement was most likely to be afterslip on the fault and the entire creep process consists of three creeping stages. Afterward, we used the steepest descent method to invert the afterslip evolution process and analyzed the relationship between post-seismic afterslip and co-seismic slip. The results witness that 447 days after the mainshock (22 September 2016), the afterslip was concentrated within one principal slip center. It was located 5–25 km along the fault strike, 0–10 km along with the fault dip, with a cumulative peak slip of 0.18 m. The 447 days afterslip seismic moment was approximately 2.65 × 1017 N m, accounting for approximately 4.1% of the co-seismic geodetic moment. The deep afterslip revealed that a creeping process from steady-state “secondary” creeping to accelerating “tertiary” creep in the deep of fault. The future seismic hazard deserves further attention and research.

Transient Behavior and Interplay Between Seismic and Aseismic Deformation Near the Tip of a Creeping Segment: Insights From the Northern Jordan Valley Segment of the Dead Sea Fault

“…Transient behavior has been found in different tectonic environments, including subduction zones, active volcanoes, and continental strike‐slip faults (e.g., Cervelli et al., 2002; Harris, 2017; Klein et al., 2019; Michel et al., 2019; Murray & Segall, 2005; Radiguet et al., 2012; Rousset et al., 2016, 2019). This behavior has been recorded during the interseismic (e.g., Klein et al., 2019; Radiguet et al., 2012), preseismic (e.g., Murray & Segall, 2005), and postseismic (e.g., Feigl & Thatcher, 2006; Wang et al., 2020) phases of the seismic cycle. It was suggested that aseismic deformation affects the nucleation, dynamic rupture, and arrest of seismic events and therefore influences the seismic potential of active faults (e.g., Avouac, 2015; Bürgmann, 2018).…”

Co- and Postseismic Deformation of the 2020 Mw 6.3 Nima (Tibet, China) Earthquake Revealed by InSAR Observations

“…In order to analyze the trend of postseismic deformation with time, the deformation of the two square areas was extracted from the postseismic deformation time series (Figure 5). The deformation time series of the extracted areas was fitted using the following logarithmic function [34].…”

Microanchored fiber-optic DSS in boreholes allows strain profiling of the shallow subsurface

“…Of the methods for vertical deformation acquisition, interferometric synthetic aperture radar (InSAR) and global navigation satellite system (GNSS) are commonly used to detect landsurface elevation changes 4 . These ground-based or remotely sensed techniques have proved to be effective in mapping large-scale ground motions 5 , but they do not allow for subsurface deformation profiles to be obtained. Drilling is a common means to determine lithology; by installing extensometers in drilled boreholes, deformations occurring at certain depths below the ground surface can be observed 6 .…”