ABSTRACT

Active blind‐thrust systems pose hidden but destructive earthquake hazards in convergent mountain fronts around the world, exemplified by the most recent 2015 Mw 6.4 Pishan event in the Hetian fold belt at the western Kunlun range front, northwest Tibetan plateau. Integrated analysis of surface geology, topography, seismic reflection profiles, and Pishan seismicity delineates the surface and subsurface geometries of the Hetian fold belt. Our results indicate that the fold belt is a segmented, active blind wedge thrust system. The Pishan event is generated by one wedge thrust segment along its leading edge: the mainshock is generated on the low‐angle fore‐thrust Slik ramp, and the aftershocks are diffusely distributed across the ramp, overlying anticline, and some unimaged structures beneath the ramp. Mapped sizes of other segments suggest that the fold belt is capable of much larger (Mw≥7.5) and more destructive earthquakes.

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