Slip rate variations on normal faults during glacial–interglacial changes in surface loads

Geologic and palaeoseismological data document a marked increase in the slip rates of the Wasatch fault and three adjacent normal faults in the Basin and Range Province during the Late Pleistocene/Early Holocene epochs. The cause of this synchronous acceleration of fault slip and the subsequent clustering of earthquakes during the Holocene has remained enigmatic, although it has been suggested that the coincidence between the acceleration of slip and the shrinkage of Lake Bonneville after the Last Glacial Maximum may indicate a causal relationship. Here we use finite-element models of a discrete normal fault within a rheologically layered lithosphere to evaluate the relative importance of two competing processes that affect fault slip: postglacial unloading (the removal of mass), which decreases the slip rate, and lithospheric rebound, which promotes faster slip. We show that lithospheric rebound caused by regression of Lake Bonneville and deglaciation of adjacent mountain ranges provides a feasible mechanism for the high Holocene rates of faulting in the Wasatch region. Our analysis implies that climate-controlled changes in loads applied to Earth's surface may exert a fundamental control on the slip history of individual normal faults.

[1]  J. Overpeck,et al.  14C Activity and Global Carbon Cycle Changes over the Past 50,000 Years , 2004, Science.

[2]  W. T. Parry,et al.  Pore fluid and seismogenic characteristics of fault rock at depth on the Wasatch Fault, Utah , 1986 .

[3]  A. Johnston.  The Effect of Large Ice Sheets on Earthquake Genesis , 1989 .

[4]  S. Willett,et al.  Exhumation of the central Wasatch Mountains, Utah: 2. Thermokinematic model of exhumation, erosion, and thermochronometer interpretation , 2003 .

[5]  P. L. La Femina,et al.  Holocene slip rate of the Wasatch fault zone, Utah, from geodetic data: Earthquake cycle effects , 2003 .

[6]  P. Basham,et al.  Earthquakes at North-Atlantic passive margins : neotectonics and postglacial rebound , 1989 .

[7]  James L. Davis,et al.  Comparison of geodetic and geologic data from the Wasatch region, Utah, and implications for the spectral character of Earth deformation at periods of 10 to 10 million years , 2003 .

[8]  S. Cadrin,et al.  A Preliminary Analysis , 2005 .

[9]  B. Wernicke,et al.  Cenozoic Tectonism in the Central Basin and Range: Motion of the Sierran-Great Valley Block , 1998 .

[10]  J. McCalpin,et al.  Holocene paleoseismicity, temporal clustering, and probabilities of future large (M > 7) earthquakes on the Wasatch fault zone, Utah , 1996 .

[11]  N. Sleep.  Isostasy and Flexure of the Lithosphere , 2002 .

[12]  M. Stein,et al.  Long-term earthquake clustering: A 50,000-year paleoseismic record in the Dead Sea Graben , 1996 .

[13]  B. Stöckhert,et al.  Elevated stresses and creep rates beneath the brittle‐ductile transition caused by seismic faulting in the upper crust , 2004 .

[14]  B. Bills,et al.  Viscosity estimates for the crust and upper mantle from patterns of lacustrine shoreline deformation in the Eastern Great Basin , 1994 .

[15]  G. Osborn.  Glaciation in the Great Basin of the Western United States , 2001 .

[16]  Patrick Wu,et al.  Induced stresses and fault potential in eastern Canada due to a realistic load: a preliminary analysis , 1996 .

[17]  Robert B. Smith,et al.  Rapid deformation rates along the Wasatch Fault Zone, Utah, from first GPS measurements with implications for earthquake hazard , 1998 .

[18]  Wayne Thatcher,et al.  The earthquake deformation cycle, recurrence, and the time‐predictable model , 1984 .

[19]  P. Steerenberg,et al.  Targeting pathophysiological rhythms: prednisone chronotherapy shows sustained efficacy in rheumatoid arthritis. , 2010, Annals of the rheumatic diseases.

[20]  B. Bills,et al.  Lake Bonneville - Constraints on lithospheric thickness and upper mantle viscosity from isostatic warping of Bonneville, Provo, and Gilbert stage shorelines , 1987 .

[21]  K. Sieh,et al.  Paleoseismic evidence of clustered earthquakes on the San Andreas Fault in the Carrizo Plain, California , 1994 .

[22]  B. Wernicke,et al.  Basin and Range Extensional Tectonics Near the Latitude of Las Vegas, Nevada , 1991 .

[23]  D. P. Schwartz,et al.  The Wasatch fault zone, utah—segmentation and history of Holocene earthquakes , 1991 .

[24]  Robert B. Smith,et al.  Chapter 12: Geophysical and tectonic framework of the eastern Basin and Range-Colorado Plateau-Rocky Mountain transition , 1989 .

[25]  J. Sauber,et al.  Glacio-seismotectonics: ice sheets, crustal deformation and seismicity , 2000 .

[26]  R. E. Wallace.  Grouping and migration of surface faulting and variations in slip rates on faults in the Great Basin province , 1987 .

[27]  Takashi Nakata,et al.  Time‐predictable recurrence model for large earthquakes , 1980 .

[28]  D. P. Schwartz,et al.  Fault behavior and characteristic earthquakes: Examples from the Wasatch and San Andreas Fault Zones , 1984 .

[29]  K. Lambeck,et al.  Postglacial rebound and fault instability in Fennoscandia , 1999 .

[30]  D. Sack,et al.  Radiocarbon chronology of Lake Bonneville, Eastern Great Basin, USA , 1992 .

[31]  D. Madsen,et al.  Late Quaternary Glacial and Vegetation Changes, Little Cottonwood Canyon Area, Wasatch Mountains, Utah , 1979, Quaternary Research.