Multisegment rupture in the 11 July 1889 Chilik earthquake (M w 8.0-8.3), Kazakh Tien Shan, interpreted from remote sensing, field survey, and paleoseismic trenching

摘要: The 11 July 1889 Chilik earthquake (M-w 8.0-8.3) forms part of a remarkable sequence large earthquakes in the late nineteenth and early twentieth centuries northern Tien Shan. Despite its importance, source remains unknown, though macroseismic epicenter is sited valley, similar to 100 km southeast Almaty, Kazakhstan (similar 2 million population). Several short fault segments that have been inferred ruptured are too on their own account for estimated magnitude. In this paper we perform detailed surveying trenching 30 long Saty fault, one previously sources, find it was formed single within last 700 years, involving surface slip up 10 m. scarp-forming event, likely be earthquake, only surface-rupturing event at least 5000 years potentially much longer. From satellite imagery extend mapped length fresh scarps epicentral zone total 175 km, which also suggest as candidate ruptures from earthquake. rupture involves conjugate oblique left-lateral right-lateral three separate faults, with step overs several kilometers between them. All faults were essentially invisible Holocene geomorphology prior slip. recurrence interval any these presumably other Shan, may longer than timescale over landscape reset, providing challenge delineating sources future hazard.