HR: 08:45h
AN: G41A-04    [Abstracts]
TI: On the comparisons of seismic moment rates determined from historic earthquakes, GPS and Quaternary fault slip rates
AU: Shen-Tu, B
EM: bingming@air-worldwide.com
AF: AIR Worldwide Corp., 131 Dartmouth St, Boston, MA 02116-5134 United States
AU: Mahdyiar, M
EM: mmahdyiar@air-worldwide.com
AF: AIR Worldwide Corp., 131 Dartmouth St, Boston, MA 02116-5134 United States
AU: * Rong, Y
EM: yrong@air-worldwide.com
AF: AIR Worldwide Corp., 131 Dartmouth St, Boston, MA 02116-5134 United States
AB: The long-term horizontal strain rate field in the India-Eurasia plate boundary zone is determined from Quaternary fault slip rates and recent GPS data. Strain rates estimated from recent GPS data in Southeastern and Northeastern China are less than 1x10-9 /yr, insignificantly different from zero, which is consistent with the rigid block or plate assumptions in recent tectonic models. We estimate the tectonic moment rates in various seismic zones in China and surrounding regions using the horizontal strain rates from the joint-inversion of geological and GPS data. The total earthquake moment rate inferred from historic earthquakes over different time periods is about 70-80 % of the total tectonic moment rate within the seismogenic volume. They are consistent with each other within one sigma confidence level. However the moment rates inferred from historic seismicity in the seismic zones containing the Kunlun fault, the Altyn Tagh fault, and Yushu-Mani fault zone in northern Tibet, the eastern Tian Shan, and Shanxi Graben system are significantly smaller than the tectonic moment rates. Our preliminary results also indicate that the extension rates across the Shanxi graben, the Weihe Basin, and Hetao basin are no more than 2 mm/yr. Nor do the left-lateral or right-lateral slip rates across these active graben systems exceed 2 mm/yr. The total horizontal slip rates across these graben structures seem to be lower than the slip rate estimates from previous studies. The discrepancies between the long-term moment rates and moment rates inferred from seismicity or geological information could have significant implications in seismic hazard calculations in China. Although the uncertainties in the current GPS data are still too large to confidently reject or modify any previous results, the addition of GPS data will no doubt help to improve uncertainties or reduce biases in seismic hazard models that are based either on historic seismicity alone or seismicity data combined with geological data.
DE: 9320 Asia
DE: 8107 Continental neotectonics
DE: 8110 Continental tectonics--general (0905)
DE: 1208 Crustal movements--intraplate (8110)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting