Depth of seismicity in the Imperial Valley Region (1977–1983) and its relationship to heat flow, crustal structure and the October 15, 1979, earthquake
- Creators
- Doser, Diane I.
-
Kanamori, Hiroo
Abstract
Focal depths from over 1000 earthquakes occuring between 1977 and 1983 in the Imperial Valley-southern Peninsular Ranges are used to study relationships between the depth of seismicity, heat flow, and crustal structure. This study used relocated A and B quality events from the California Institute of Technology catalog that were carefully selected to insure focal depth precision of ±2 km. Regional variations in focal depth appear to be related to regional heat flow variation, whereas local variations in focal depth, especially in the central Imperial Valley, may be related to crustal structure. These variations are studied by rheologic modeling. A comparison of focal depths of earthquakes occurring before and after the October 15, 1979 (M=6.6), earthquake indicates that aftershocks during the first 2 months of the sequence were 2–3 km deeper than earthquakes occurring in other time periods. The deepest earthquakes in Imperial Valley are spatially associated with a subbasement dome near the northern end of the Imperial fault. This dome coincides with the region where the Imperial fault undergoes a transition from stick-slip behavior to aseismic fault creep. Models of slip during the 1979 mainshock are also compared with premainshock and postmainshock seismicity. A relocation of the 1940 (M=7.1) mainshock suggests that this sequence began by rupturing the same portion of the fault that experienced maximum slip during the 1979 mainshock.
Additional Information
© 1986 by the American Geophysical Union. Received April 17, 1985; revised October 7, 1985; accepted October 11, 1985. We would like to thank A. Frankel and S. Wesnousky for their helpful discussions and comments. T. Webb wrote many of the programs used in accessing the phase data. A. Lachenbruch kindly provided us with a preprint of the Salton Trough heat flow paper. J. Pechmann and M. Baker reviewed a preliminary version of the manuscript. Comments by an anonymous reviewer and an associate editor were also appreciated. This work was supported by U.S. Geological Survey contract 14-08- 0001-21981. D. Doser was also supported by a Caltech Bantrell postdoctoral fellowship. Contribution 4258, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena.Attached Files
Published - HKjgr86b.pdf
Files
| Name | Size | Download all |
|---|---|---|
|
md5:cf1f568027861c5e1a49b907b1550b91
|
1.1 MB | Preview Download |
Additional details
- Eprint ID
- 52864
- Resolver ID
- CaltechAUTHORS:20141216-110133754
- 14-08-0001-21981
- USGS
- Caltech Bantrell postdoctoral fellowship
- Created
-
2014-12-16Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences
- Other Numbering System Name
- Caltech Division of Geological and Planetary Sciences
- Other Numbering System Identifier
- 4258