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Surface Rupture From an Aftershock: Remote Observations From the January 2024 Wushi (Aykol) Earthquakes, China

Description: 

On January 22, 2024, a moment magnitude (Mw) 7.0 earthquake occurred in the southern Tian Shan region of western China, followed by a Mw 5.7 aftershock on January 29. Interferometric synthetic aperture radar (InSAR) observations and a lack of observed surface rupture in optical satellite imagery between January 22 and 26 indicated the Mw 7.0 rupture was blind. The location and depth of the Mw 7.0 mainshock is consistent with southeast-vergent thrust motion on the mapped range-front Maidan fault along the southern Tian Shan. However, sub-pixel correlation of independent high-resolution optical satellite imagery and post-mainshock InSAR observations spanning the Mw 5.7 aftershock shows ~4.8 km of discontinuous surface rupture with a south-side-up sense of motion. The trend of the surface rupture is northeast-southwest, similar to that of the bedding orientation within the limb of a previously mapped syncline. Sub-pixel image correlation and digital elevation model differencing show mean surface displacements of 0.6 m, with a peak of ~1 m, along the fault near the center of the mapped surface rupture trace. Given these observations, we interpret the Mw 5.7 aftershock produced surface rupture on an unmapped flexural slip fault within a syncline in the hanging wall of the Maidan fault or on a backthrust associated with the Maidan fault. Importantly, this difference in observed surface rupture between the larger magnitude mainshock and smaller magnitude aftershock is a critical observation that highlights the need to understand secondary or distributed faulting associated with larger earthquakes that rupture either coseismically with the mainshock or during an aftershock. Such secondary faults may represent potentially poorly constrained hazards that should be considered during seismic and fault displacement hazard analysis and earthquake response.

Session: Unusual Earthquakes and Their Implications [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Jessica

Student Presenter: No

Invited Presentation: 

Poster Number: 14

Authors