TY - JOUR

T1 - Long-term rates of faulting derived from cosmogenic nuclides and short-term variations caused by glacial-interglacial volume changes of glaciers and lakes

AU - Hetzel, Ralf

AU - Hampel, Andrea

N1 - Funding information: R. Hetzel thanks his co-workers in the projects in Tibet: M. Tao (Chinese Academy of Science Lanzhou), M. Strecker (Institut für Geowissenschaften, Universität Potsdam), S. Niedermann (GeoForschungsZentrum Potsdam), P. Kubik and S. Ivy-Ochs (Institute of Particle Physics, ETH Zurich). The numerical experiments have been performed at the Institute of Geology, University of Bern. Discussions with A. Pfiffner, C. Schlüchter and U. Jörin of the Universität Bern as well as with A. Densmore (Department of Earth Sciences, ETH Zurich) and A. Friedrich (Institut für Geologie und Paläontologie, Universität Hannover) are gratefully acknowledged. Funding for the projects in Tibet was provided by the German Research Foundation (DFG).

PY - 2006/1/30

Y1 - 2006/1/30

N2 - Seismic hazard evaluations on major faults in Earth's crust are based on their slip histories, which reflect the frequency of earthquakes that ruptured a fault in the past. On a 100 000-year timescale, the slip rate of a fault can be determined by dating geomorphic surfaces that are offset by a fault. Application of this method to alluvial fan surfaces and river terraces offset by thrust faults in Tibet yields long-term slip rates of less than 1mm/a. Slip rates on a 10 000-year timescale are derived from paleoseismologic data and document that faults experience considerable slip rate variations on timescales of 100 to 1000 years. In particular, slip rates are often considerable higher in the present interglacial, the Holocene, than during the last glacial period, the Late Pleistocene. The causes of this behavior have remained enigmatic but their assessment is essential for an accurate evaluation of a fault's past and future seismicity. Numerical experiments show that the retreat of lakes and glaciers at the end of the last glacial period can cause an increase in the Holocene slip rate of a fault. Such a correlation between enhanced seismicity and climate-driven mass fluctuations on Earth's surface is best documented for the Wasatch Fault, Utah.

AB - Seismic hazard evaluations on major faults in Earth's crust are based on their slip histories, which reflect the frequency of earthquakes that ruptured a fault in the past. On a 100 000-year timescale, the slip rate of a fault can be determined by dating geomorphic surfaces that are offset by a fault. Application of this method to alluvial fan surfaces and river terraces offset by thrust faults in Tibet yields long-term slip rates of less than 1mm/a. Slip rates on a 10 000-year timescale are derived from paleoseismologic data and document that faults experience considerable slip rate variations on timescales of 100 to 1000 years. In particular, slip rates are often considerable higher in the present interglacial, the Holocene, than during the last glacial period, the Late Pleistocene. The causes of this behavior have remained enigmatic but their assessment is essential for an accurate evaluation of a fault's past and future seismicity. Numerical experiments show that the retreat of lakes and glaciers at the end of the last glacial period can cause an increase in the Holocene slip rate of a fault. Such a correlation between enhanced seismicity and climate-driven mass fluctuations on Earth's surface is best documented for the Wasatch Fault, Utah.

KW - Cosmogenic nuclides

KW - Finite-element modeling

KW - Tectonophysics

UR - http://www.scopus.com/inward/record.url?scp=32644446427&partnerID=8YFLogxK

U2 - 10.1142/S0217979206033255

DO - 10.1142/S0217979206033255

M3 - Article

AN - SCOPUS:32644446427

VL - 20

SP - 261

EP - 276

JO - International Journal of Modern Physics B

JF - International Journal of Modern Physics B

SN - 0217-9792

IS - 3

ER -