Late Quaternary rate of slip along the San Jacinto fault zone near Anza, southern California
- San Diego Univ., CA (United States)
- Lamar-Merifield Geologists, Inc., Santa Monica, CA (United States)
The Anza section of the San Jacinto fault, southern California, has not experienced a ground-breaking earthquake since at least 1918 and probably since before 1899, leading previous workers to designate this 20-km-long fault segment as a seismic gap. Study of displaced Pleistocene and Holocene alluvial fan and fluvial deposits across the San Jacinto fault near Anza, California, dated using {sup 14}C and soil development age control, indicates a minimum right-lateral slip rate of 9.2 {plus minus} 2 mm/yr since 9.5 ka, and a slip rate of 11{sub {minus}5}{sup +9} mm/yr since 14 ka, 12{sub {minus}5}{sup +9} mm/yr since 17 ka, and 13{sub {minus}6}{sup +10} mm/yr since 50 ka. These estimates agree with a previously determined 700 ka to present minimum slip rate of 10 {plus minus} 2 mm/yr. Based on an estimated average slip rate of 12 mm/yr from the longer-term slip rate estimates, about 0.8 m of potential slip has accumulated if the 1918 earthquake broke the Anza segment; over 1.1 m of potential slip has accumulated if the last earthquake occurred prior to 1899. These data attest to the potential for an earthquake {ge}M6.5 for this section of the fault.
- OSTI ID:
- 5009579
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 95:B6; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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