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Satellite Optical Image Correlation Measurements for a Moderate Magnitude Thrust Earthquake: The January 2024 Wushi (Aykol), China Mw 5.7 Aftershock

Description: 

Sub-pixel optical image correlation has become a standard tool in earthquake deformation studies, filling key spatial and temporal gaps in data coverage for large magnitude events. The method, however, has rarely been employed to document small to moderate magnitude earthquake deformation. On January 22nd, 2024, a blind Mw 7.0 rangefront thrust earthquake occurred in the southern Tian Shan of China on the northwest-dipping Maidan fault. Although the mainshock did not rupture to the surface, a Mw 5.7 aftershock on January 29^th, 2024 ruptured an oppositely-dipping thrust fault, yielding a NE-trending ~4.8-km-long surface rupture with vertical displacements high enough to temporarily pond the Qialemati River. High-resolution (0.5 m) satellite optical imagery available within the month following the aftershock presents an opportunity to remotely derive near-fault three-dimensional kinematic information via pre- and post-earthquake sub-pixel image correlation and digital elevation model differencing. This study is particularly challenging and atypical in the context of previous imagery-based three-dimensional displacement analyses because of the relatively small displacements (<2 m) that were primarily vertical rather than horizontal. Additional epistemic uncertainties enter our analyses due to sub-optimal image quality, including oblique image capture in a non-stereo configuration, different sensor platforms, cloud cover, and intervening snow cover. Field measurements collected along the surface rupture immediately following the event provide ground-truth comparison for the remotely derived kinematics. Together, the two datasets complement each other for both earthquake response and discerning displacement characteristics of a surprising surface rupture from a moderate magnitude aftershock.

Session: Unusual Earthquakes and Their Implications - I

Type: Oral

Date: 4/16/2025

Presentation Time: 02:45 PM (local time)

Presenting Author: Catherine

Student Presenter: No

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