Seismic Constraints and Coulomb Stress Changes of a Blind Thrust Fault System, 1: Coalinga and Kettleman Hills, California
Entry ID:
USGS_OFR_2006_1149
Summary This report reviews the seismicity and surface ruptures associated with the 1982-1985 earthquake sequence in the Coalinga region in California, and the role of Coulomb stress in triggering the mainshock sequence and aftershocks. The 1982-1985 New Idria, Coalinga, and Kettleman Hills earthquakes struck on a series of west-dipping, en echelon blind thrust faults. Each ... earthquake was accompanied by uplift of a Quaternary anticline atop the fault, and each was accompanied by a vigorous aftershock sequence. Aftershocks were widely dispersed, and are seen above and below the thrust fault, as well as along the up-dip and down-dip projection of the main thrust fault. For the Coalinga and Kettleman Hills earthquakes, high-angle reverse faults in the core of the anticlines are evident in seismic reflection profiles, and many of these faults are associated with small aftershocks. The shallowest aftershocks extended to within 3-4 km of the ground surface. There is no compelling evidence for aftershocks associated with flexural slip faulting. No secondary surface rupture was found on any of the anticlines. In contrast, the 1983 Nunez rupture struck on a high-angle reverse fault 10 km west of the Coalinga epicenter, and over a 40-80-day period, up to 1 m of oblique surface slip occurred. The slip on this Holocene fault likely extended from the ground surface to a depth of 8-10 km. We argue that both the Nunez and Kettleman earthquakes were triggered by stresses imparted by the Coalinga mainshock, which was the largest of the four events in the sequence.
[Summary provided by the USGS.] Geographic Coverage
Spatial coordinates
N: 37.0
S: 34.0
E: -117.0
W: -122.0
Data Set Citation
Dataset Creator:
Jian Lin and Ross S. Stein
Dataset Title:
Seismic Constraints and Coulomb Stress Changes of a Blind Thrust Fault System, 1: Coalinga and Kettleman Hills, California
Dataset Series Name:
Open File Report
Dataset Release Date:
2006
Dataset Publisher:
U.S. Geological Survey
Issue Identification:
OFR 2006-1149
Online Resource:
http://pubs.usgs.gov/of/2006/1149/
Name:
MICHAEL
F.
DIGGLES Phone:
(650) 329-5404
Email:
mdiggles at usgs.gov
Contact Address:
U.S. Geological Survey
345 Middlefield Road
Mail Stop 531 City:
Menlo Park
Province or State:
CA
Postal Code:
94025
Country:
USA
Personnel
ROSS
STEIN Role:
TECHNICAL CONTACT
Phone:
(650) 329-4840
Email:
rstein at usgs.gov
Contact Address:
345 Middlefield Rd MS 977 City:
Menlo Park
Province or State:
CA
Postal Code:
94025
Country:
USA
Related URL
Link:
VIEW RELATED INFORMATION
Description:
Report on the Seismic Constraints and Coulomb Stress Changes of a Blind Thrust
Fault System, 1: Coalinga and Kettleman Hills, California.
Creation and Review Dates
DIF Creation Date:
2006-06-14
Last DIF Revision Date:
2006-06-15
Links
