HR: 0830h
AN: T21D-0480    [PDF]
TI: Further Confirmation of a Low Slip Rate on the Altyn Tagh Fault
AU: * Wallace, K
EM: kali@cires.colorado.edu
AF: University of Colorado, Department of Geological Sciences, Box 399, Boulder, CO 80305
AU: Yin, G
EM: yinguhua@mail.xj.cninfo.net
AF: Seismological Bureau of Xinjiang, No. 42 South Beijing Road, Urumqi, XJ 830011 China
AU: Bilham, R
EM: bilham@colorado.edu
AF: University of Colorado, Department of Geological Sciences, Box 399, Boulder, CO 80305
AB: Estimates of slip rate inferred from geodetic data on the 2000-km-long Altyn Tagh fault, on the northern edge of the Tibetan Plateau, are 2-3 times lower than those estimated from several investigations of geologic offsets. Geodetic measurements by our group in 1994-8 indicated a slip rate of 9ñ4 mm/yr, subsequently confirmed by several other investigators. Recent PRC estimates yield yet lower rates on the eastern half of the fault (5 mm/yr). In 2002, points on a 300-km-long GPS profile between 88?-91? E, previously measured in 1994 and 1998, were occupied for a third time, and a shorter profile at 85?, first measured in 1998, was occupied for the second time. Geodetic rates calculated from the data obtained in 2002 indicate left-lateral strike-slip motion of 5ñ7 mm/yr on the eastern profile and 5ñ10 mm/yr on the 60 km western profile. Rates of convergence on the two profiles are found to be 3 +/- 1 mm/yr and 2 +/- 1 mm/yr, respectively. Two large strike slip earthquakes occurred during the span of our measurements. When our data are corrected for elastic displacements inferred from these events the 1994-98 rate is changed insignificantly, and the 1998-02 is increased by approximately 2 mm/year. Our preferred rate for the central Altyn Tagh fault is thus approximately 7 mm/year, a number that will undoubtedly have been refined somewhat by the time of the meeting. The eight year record of geodetic data leaves little maneuvering room, and thus the geologic and modern slip rates are not reconciled.
DE: 1208 Crustal movements--intraplate (8110)
DE: 8110 Continental tectonics--general (0905)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting