HR: 1340h
AN: T23D-1635    [Abstracts]
TI: The Hunt for Surface Rupture From the 1889 Ms 8.3 Chilik Earthquake, Northern Tien Shan, Kyrgyzstan and Kazakhstan
AU: * Crosby, C J
EM: chris.crosby@asu.edu
AF: Arizona State University, School of Earth and Space Exploration, PO Box 871404, Tempe, AZ 85287-1404, United States
AU: Arrowsmith, J R
EM: ramon.arrowsmith@asu.edu
AF: Arizona State University, School of Earth and Space Exploration, PO Box 871404, Tempe, AZ 85287-1404, United States
AU: Korjenkov, A M
EM: akorjen@elcat.kg
AF: Kyrgyz Institute of Seismology NAS KR, Asanbay 52/1, Bishkek, 720060, Kyrgyzstan
AU: Guralnik, B
EM: benny.guralnik@gmail.com
AF: The Hebrew University, Institute of Earth Sciences, Givat Ram, Jerusalem, 91904, Israel
AU: Mamyrov, E
EM: akorjen@elcat.kg
AF: Kyrgyz Institute of Seismology NAS KR, Asanbay 52/1, Bishkek, 720060, Kyrgyzstan
AU: Povolotskaya, I E
EM: povira30@rambler.ru
AF: Kyrgyz Institute of Seismology NAS KR, Asanbay 52/1, Bishkek, 720060, Kyrgyzstan
AB: The 1889 Ms 8.3 Chilik earthquake in the Northern Tien Shan Mountains of Kyrgyzstan and Kazakhstan is one of the largest historic intraplate reverse-faulting events. Documentation of slip distribution and fault geometry for major historic earthquakes, such as the Chilik event, provide important data on their source physics, seismotectonics, and hazard. These data also provide insight into potential mechanical interaction with other large regional earthquakes, notably the 1887 Ms 7.3 Verny and 1911 Ms 8.2 Kebin (Chon Kemin) events. Despite the importance of the Chilik event, very little is known about the earthquake's epicenter and the presence of associated ground rupture. Isoseismal's from historic shaking intensity data gathered immediately following the event were used to estimate the event magnitude and suggest an epicentral location in the northern foothills of the Kungey Ala-too range, 80-100 kilometers east-southeast of Almaty. Researchers who have visited this area report no evidence of ground rupture, suggesting that the event either did not rupture the ground surface or that the isoseismal data do not provide a sufficiently focused estimate of epicentral location. We have reanalyzed the shaking intensity data to update the estimate of the epicentral location. During June 2007 field work and in review of aerial photography, we observed extensive east-west trending and morphologically youthful km-long and 1-5 m high fault scarps on the eastern crest of the Kungey Ala-Too Range along the Kygyz-Kazak border north of Tyup. Contemporary reports of the 1911 Kebin earthquake did not document these structures, despite the thorough investigation of rupture to the west and northwest. The scarp lengths and their offsets indicate that they did not form in the M6.6 1978 Djalanash Tyup earthquake. Although located to the south of the isoseismal epicenter for the Chilik earthquake, the scarps observed near the range crest must be considered as possible candidates for Chilik ground rupture.
DE: 7221 Paleoseismology (8036)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8102 Continental contractional orogenic belts and inversion tectonics
DE: 8107 Continental neotectonics (8002)
DE: 8108 Continental tectonics: compressional
SC: Tectonophysics [T]
MN: 2007 Fall Meeting