HR: 09:20h
AN: T31E-06    [Abstracts]
TI: Slip-distribution and Rupture Pattern of the 14 November 2001, Mw 7.8 Kokoxili Earthquake (China)
AU: * Klinger, Y
EM: klinger@ipgp.jussieu.fr
AF: Tectonique - IPGP, UMR7578 - BP89 4 place Jussieu, Paris, 75005 France
AU: Michel, R
EM: remi.michel@cea.fr
AF: LDG/CEA, BP12, Bruyeres le Chatel, 91680 France
AU: Van der Woerd, J
EM: jeromev@eost.u-strasbg.fr
AF: EOST, 5 rue Descartes, Strasbourg, 67000 France
AU: Xu, X
EM: xiweixu@vip.sina.com
AF: Institut of Geology, Chinese Earthquake Administration, Beijing, 100029 China
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: Tectonique - IPGP, UMR7578 - BP89 4 place Jussieu, Paris, 75005 France
AB: The Mw=7.8 Kokoxili earthquake ruptured about 430 km of the Kusai segment of the Kunlun fault (from 90.2E to 94.7E). This event, the largest continental event ever recorded in Asia, follows nearly four years later, the 8 November 1997, Mw=7.6 Manyi earthquake. The surface break follows the geomorphic trace of the fault, which bears evidence for cumulative displacements. Using Ikonos and Quickbird satellite images with nominal resolution of 1m and 60cm, respectively, we mapped in detail the central segment of the rupture and documented the slip-partitioning process that took place during the earthquake rupture. Some new details about the rupture in the epicentral area west of the Tayang Lake are also presented. From field explorations of the rupture we show evidences for normal fault breaks and left-lateral ruptures along the steep faceted southern flank of the BukaDaban Feng, a 40km-long range reaching 6800m asl. Hence this mountain range clearly results from continuous oblique left-lateral faulting along the extensional corridor connecting the epicenter area to the main rupture segment. Due to the remoteness and harsh climatic condition of the earthquake location, an exhaustive survey of the entire fault rupture is difficult. While several teams have been involved in measuring geomorphic offsets due to this earthquake. The amount of data collected, however, remains small compared to the length of the rupture. Also considering the complexity of the rupture, measuring the earthquake dislocation has proved to be difficult in many places and has raised arguments about the shape of the slip-curve and the maximum horizontal offset associated to the Kokoxili earthquake. Using sub-pixel intercorrelation of optical satellite images (satellite Spot, pixel 10m) we produced a slip-curve that encompasses the entire rupture with an independent measurement every kilometer on average. This technique allows us to detect displacement down to 1m. The slip-distribution we obtained shows clearly that the maximum slip is highly localized on few asperities whereas it remains moderate (<4m) along large parts of the rupture. The maximum slip we could measure is 12m, which is much lower than some values previously reported. The large variation of slip along the rupture for a single event bears important consequences and should be seriously considered when long-term rupture behavior of the fault is discussed based on cumulative offset measurements or paleoseismological investigation.
DE: 9320 Asia
DE: 7230 Seismicity and seismotectonics
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting