HR: 14:45h
AN: T33F-05    [Abstracts]
TI: Earthquake Surface Rupture of the Salt Range Thrust at the Himalayan Thrust Front in Pakistan
AU: Meigs, A
EM: meigsa@geo.oregonstate.edu
AF: Department of Geosciences, 104 Wilkinson Hall Oregon State University, Corvallis, OR 97331, United States
AU: Yule, J D
EM: Doug.Yule@csun.edu
AF: Department of Geological Sciences, California State University, Northridge, Northridge, CA 91330-8266, United States
AU: * Madden, C
EM: madden@earthconsultants.com
AF: Department of Geosciences, 104 Wilkinson Hall Oregon State University, Corvallis, OR 97331, United States
AU: * Madden, C
EM: madden@earthconsultants.com
AF: Earth Consultants International, 150 El Camino Real, Suite 212, Tustin, CA 92780, United States
AU: Yeats, R
EM: yeatsr@geo.oregonstate.edu
AF: Department of Geosciences, 104 Wilkinson Hall Oregon State University, Corvallis, OR 97331, United States
AU: Yeats, R
EM: yeatsr@geo.oregonstate.edu
AF: Earth Consultants International, 150 El Camino Real, Suite 212, Tustin, CA 92780, United States
AU: Hussain, A
EM: ahussain@brain.net.pk
AF: Earth Consultants International, 150 El Camino Real, Suite 212, Tustin, CA 92780, United States
AU: Hussain, A
EM: ahussain@brain.net.pk
AF: Geological Survey of Pakistan, P.O. Box 1355, Peshawar, 25120, Pakistan
AU: Akhtar, S S
EM: sardarakhtar305@yahoo.com
AF: Geological Survey of Pakistan, P.O. Box 1355, Peshawar, 25120, Pakistan
AU: Latif, A
EM: gsp-pesh@yahoo.com
AF: Geological Survey of Pakistan, P.O. Box 1355, Peshawar, 25120, Pakistan
AU: Waliullah, A
EM: gsp-pesh@yahoo.com
AF: Geological Survey of Pakistan, P.O. Box 1355, Peshawar, 25120, Pakistan
AU: Ashraf, M
EM: mashraf73@yahoo.com
AF: Geological Survey of Pakistan, P.O. Box 1355, Peshawar, 25120, Pakistan
AU: Ramzan, S
EM: shahidmuj@hotmail.com
AF: Geological Survey of Pakistan, P.O. Box 1355, Peshawar, 25120, Pakistan
AU: Dasti, N
EM: dastigeo@yahoo.com
AF: Geological Survey of Pakistan, P.O. Box 1355, Peshawar, 25120, Pakistan
AB: Considerable evidence from Nepal and India now indicates that the basal detachment of the Himalaya produces great earthquakes that result in large coseismic displacements at the thrust front in India and Nepal (the Main Frontal thrust). In contrast, knowledge of the earthquake potential of the Salt Range thrust in Pakistan (SRT) is virtually absent. It has been clear since the publication of the Salt Range maps of Gee (1989) that the SRT deforms young surficial deposits and is an active fault. What remains uncertain is whether surface rupturing events occur on the SRT, with what frequency those events occur, and what is the size of the associated earthquakes. In a field reconnaissance of the SRT in Spring, 2007, we were able to confirm that this thrust is an active fault, and we discovered numerous localities where the fault nearly reaches the surface, cutting all but the youngest few meters of colluvial deposits. Whereas our observations suggest that surface rupturing events occur on the SRT, a number of characteristics of the Pakistani Himalaya suggests the earthquake behavior of the basal detachment and thrust front may be substantially different than it is in India and Nepal to the southeast. Key differences include an uncertain, but lower, convergence rate at the thrust front (5 to 13 mm/yr), a low tapered thrust wedge, and localization of the basal detachment in a weak evaporite unit. In this sense, the front of the Zagros fold-and-thrust belt in Iran may be a more appropriate analog for the thrust front in Pakistan than the Himalayan thrust front to the southeast. Future mapping of deformed geomorphic surfaces and paleoseismic trenching along the SRT will provide the first direct evidence of the earthquake potential and recurrence of plate- boundary earthquakes in Pakistan. This knowledge is critical for hazard assessment in north-central Pakistan where more than 7 million people are likely to be affected by a great earthquake on the plate boundary.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8002 Continental neotectonics (8107)
DE: 8036 Paleoseismology (7221)
DE: 8104 Continental margins: convergent
SC: Tectonophysics [T]
MN: 2007 Fall Meeting