Interseismic strain and rotation rates in the northeast Mojave domain, eastern California

Journal of Geophysical Research B: Solid Earth
By: , and 

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Abstract

The northeast Mojave domain, a type locality for bookshelf faulting, is a region of east striking, left-lateral faults in the northeast corner of the Mojave block, a block otherwise dominated by ∼N40°W striking, right-lateral faults. Paleomagnetic evidence suggests that blocks within the domain have rotated clockwise about a vertical axis as much as 60° since 12.8 Ma [Schermer et al., 1996]. In 1994, and again in 2002, the U.S. Geological Survey surveyed an array of 14 geodetic monuments distributed across the northeast Mojave domain. The 2002 survey results were adjusted to remove the coseismic offsets imposed by the nearby Hector Mine earthquake (16 October 1999, Mw = 7.1). The adjusted deformation across the array appears to be uniform and can be approximated by the principal strain rates ε1 = 28.9 ± 9.1 N77.2°W ± 4.8° and ε2 = −48.2 ± 8.9 N12.8°E ± 4.8° nstrain yr−1; extension reckoned positive, and quoted uncertainties are standard deviations. That strain accumulation could be released by slip on faults striking N32°W but not by bookshelf faulting on the east striking faults alone. The vertical axis rotation rate of the northeast Mojave domain as a whole relative to fixed North America is 71.0 ± 6.4 nrad yr−1 (4.07° ± 0.37° Myr−1) clockwise, about twice the maximum tensor shear strain rate. The observed rotation rate acting over 12.8 Myr would produce a clockwise rotation of 52.1° ± 4.7°, exclusive of possible coseismic rotations. That rotation is in rough agreement with the paleomagnetic rotation accumulated in the individual fault blocks within the northeast Mojave domain since 12.8 Ma.

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Publication type Article
Publication Subtype Journal Article
Title Interseismic strain and rotation rates in the northeast Mojave domain, eastern California
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1029/2003JB002705
Volume 109
Issue 2
Year Published 2004
Language English
Publisher Wiley
Contributing office(s) Earthquake Science Center
Description 13 p.
Country United States
State California
Other Geospatial Mojave
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