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Late-Holocene rupture history of the Rose Canyon Fault in Old Town, San Diego; implications for cascading earthquakes on the Newport-Inglewood-Rose Canyon fault system

Drake M. Singleton, Thomas K. Rockwell, Diane Murbach, Monte Murbach, Jillian M. Maloney, Tom Freeman and Yuval Levy
Late-Holocene rupture history of the Rose Canyon Fault in Old Town, San Diego; implications for cascading earthquakes on the Newport-Inglewood-Rose Canyon fault system
Bulletin of the Seismological Society of America (March 2019) Pre-Issue Publication

Abstract

We present new results from paleoseismic trenches excavated across the main trace of the Rose Canyon fault zone (RCFZ) in Old Town-San Diego, California, to determine the timing of late-Holocene earthquakes. There is evidence for four large surface-rupturing events, as well as two smaller events, the youngest of which cuts the early historical living surface that contains glass, ceramics, and a historical era foundation. This youngest event is likely related to the 1862 San Diego earthquake, which had an estimated magnitude close to M 6. The age of older ruptures is constrained by 36 radiocarbon dates that exhibit good stratigraphic order. The four larger events produced substantially more ground deformation, and over a broader width of the fault zone, than the 1862 event. The youngest of the four larger events is found immediately below the historical horizon and likely correlates with the most recent event recognized at multiple trench sites along the RCFZ in San Diego and dates to the mid-1700s. The three older events have all occurred in the past 3300 yr, with the penultimate large event dated to about A.D. 1300. The results of this paleoseismic study indicate that the RCFZ has sustained activity throughout the late-Holocene and into the historical period. These results also suggest that the RCFZ has a late-Holocene recurrence interval of approximately 700 yr, which is several hundred years shorter than previous estimates. Comparison of RCFZ paleoseismic results with paleoseismic data from the Newport-Inglewood fault zone (NIFZ) shows that some RCFZ earthquakes have similar timing with NIFZ events, most likely indicating the occurrence of a sequence or cluster of events on the coastal system of strike-slip faults. The alternative explanation-very large earthquakes rupturing both faults simultaneously-is unlikely when both the slip rate and recurrence intervals for these faults are considered.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: Pre-Issue Publication
Title: Late-Holocene rupture history of the Rose Canyon Fault in Old Town, San Diego; implications for cascading earthquakes on the Newport-Inglewood-Rose Canyon fault system
Affiliation: San Diego State University, Department of Geological Sciences, San Diego, CA, United States
Published: 20190326
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 53
Accession Number: 2019-029450
Categories: SeismologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., 1 table, sketch maps
N31°00'00" - N34°00'00", W120°00'00" - W115°00'00"
Secondary Affiliation: Murbach Geotech, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201916
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