The transfer of slip between two en echelon strike-slip faults : a case study from the 1992 Landers earthquake, southern California
Date of Issue1995
Detailed mapping of the fresh surficial ruptures in the right step between the Homestead Valley Fault and the Emerson Fault, two right-lateral en echelon faults that broke in the 1992 Landers earthquake, indicates that the transfer of dextral slip between the faults is accommodated primarily by a series of obliquely striking right-lateral strike-slip cross faults. Right-lateral slip on the cross faults and counterclockwise rotation of the interior blocks are sufficient to transfer virtually 100% of the dextral slip and to accommodate the extension across the jog. Asymmetry of the dextral slip curves along the cross faults indicates that some of them may have been induced to fail by slip on the Homestead Valley Fault, while others were induced to fail by slip on the Emerson Fault. Comparison of the magnitude of slip in 1992 to bedrock and geomorphic offsets suggests that the Homestead Valley Fault and several secondary faults have experienced about 100 nominal Landers events and that the stepover structure originated at the same time as the Homestead Valley Fault, about 1 m.y. ago. Because the Emerson Fault has an order of magnitude greater total offset but only slightly greater surficial slip in 1992, we conclude that it is a significantly older fault. Repetition of 1992-like events should eventually lead to a merging of the Homestead Valley Fault with the Emerson.
DRNTU::Science::Geology::Volcanoes and earthquakes
Journal of geophysical research
© 1995 American Geophysical Union. This paper was published in Journal of Geophysical Research and is made available as an electronic reprint (preprint) with permission of American Geophysical Union. The paper can be found at the following official URL: http://dx.doi.org/10.1029/95JB00918. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.