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Earthquake Monitoring in Southern California for Seventy-Seven Years (1932–2008)

Hutton, Kate and Woessner, Jochen and Hauksson, Egill (2010) Earthquake Monitoring in Southern California for Seventy-Seven Years (1932–2008). Bulletin of the Seismological Society of America, 100 (2). pp. 423-446. ISSN 0037-1106. doi:10.1785/0120090130.

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The Southern California Seismic Network (SCSN) has produced the SCSN earthquake catalog from 1932 to the present, a period of more than 77 yrs. This catalog consists of phase picks, hypocenters, and magnitudes. We present the history of the SCSN and the evolution of the catalog, to facilitate user understanding of its limitations and strengths. Hypocenters and magnitudes have improved in quality with time, as the number of stations has increased gradually from 7 to ~400 and the data acquisition and measuring procedures have become more sophisticated. The magnitude of completeness (M_c) of the network has improved from M_c ~3.25 in the early years to M_c ~1.8 at present, or better in the most densely instrumented areas. Mainshock–aftershock and swarm sequences and scattered individual background earthquakes characterize the seismicity of more than 470,000 events. The earthquake frequency-size distribution has an average b-value of ~1.0, with M≥6.0 events occurring approximately every 3 yrs. The three largest earthquakes recorded were 1952 M_w 7.5 Kern County, 1992 M_w 7.3 Landers, and 1999 M_w 7.1 Hector Mine sequences, and the three most damaging earthquakes were the 1933 M_w 6.4 Long Beach, 1971 M_w 6.7 San Fernando, and 1994 M_w 6.7 Northridge earthquakes. All of these events ruptured slow-slipping faults, located away from the main plate boundary fault, the San Andreas fault. Their aftershock sequences constitute about a third of the events in the catalog. The fast slipping southern San Andreas fault is relatively quiet at the microseismic level and has not had an M>6 earthquake since 1932. In contrast, the slower San Jacinto fault has the highest level of seismicity, including several M>6 events. Thus, the spatial and temporal seismicity patterns exhibit a complex relationship with the plate tectonic crustal deformation.

Item Type:Article
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URLURL TypeDescription DOIArticle
Hauksson, Egill0000-0002-6834-5051
Additional Information:© 2010 Seismological Society of America. Manuscript received 2 June 2009. A huge cast of individuals has worked on the data processing for the Southern California earthquake catalog over time. It is not possible to name them all, but the following come to mind: C. R. Allen, V. Appel, A. C. Blanchard, A. S. Bryant, A. Burciaga, S. B. Choi, J. Cooper, J. Cronk, A. Dejohn, R. Ewald, J. Franck, S. A. Fischer,D. Ford, M. Fouch, W. Franzen, M. E. Friedman, G. S. Fuis, K. Kahler, R. R. Geary, L. Gee, P. T. German, D. D. Given, S. Green, A. J. Guarino, G. Gutierrez, J. Haas, K. Hafner, W. Heaton, J. A. Hileman, W. Huston, D. J. Jenkins, C. E. Johnson, M. Johnson, L. M. Jones, G. Killeen, V. D. Lamanuzzi, C. Loeffler, J. Mori, J. M. Nordquist, R. Norris, S. Perry, R. Peters, J. Polet, H. Qian, B. A. Reed, C. F. Richter, K. J. Richter, E. Riggs, R. Robb, P. Roberts, H. Rico, N. J. Scheckel, V. Taylor, M. Turner, L. A. Wald, K. M. Watts, D. Wells, J. H. Whitcomb, and B. Wu. An additional host of people, including but not limited to J. Batten, R. Bhadha, L. Blaney, G. Cone, R. Cone, W. Curtis, A. Devora, R. S. Dollar, D. J. Johnson, C. Koesterer, F. Lehner, J. Lower, S. Lydeen, P. Maechling,W. Miller, J. Romo, T. Saleh, S. Schwarz, P. Small, R. A. Taylor, and A.W.Walter, have installed and maintained the stations, the computer hardware, and written the software. B. Wu and E. Yu helped with figures, and M. Boese, G. Cua, K. Felzer, L. Jones, H. Kanamori, A. Michael, and one anonymous reviewer provided comments that improved the manuscript. The Southern California Earthquake Data Center (SCEDC) (lead by R. Clayton and E. Yu) archives and distributes the SCSN data. The SCSN has been supported by NEHRP/USGS and ANSS through a series of Cooperative Agreement (the most recent is # 07HQAG0007), the California Emergency Management Agency (CalEMA) through a series of contracts (the most recent is # 6028-2), and the IRIS/USArray and IRIS/GSN through Contract Numbers 473 and 310; the SCEDC is supported by SCEC that is funded by NSF Cooperative Agreement EAR-0529922 and USGS Cooperative Agreement 07HQAG0008. Caltech, Division of Geological and Planetary Sciences, Seismological Laboratory contribution number 10024. SCEC contribution number 1277.
Group:Seismological Laboratory, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
California Emergency Management Agency6028-2
Incorporated Research Institutions for Seismology/USArray and Incorporated Research Institutions for Seismology/GSN473
Incorporated Research Institutions for Seismology/USArray and Incorporated Research Institutions for Seismology/GSN310
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences10024
Southern California Earthquake Center1277
Issue or Number:2
Record Number:CaltechAUTHORS:20100412-100328789
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Official Citation:Kate Hutton, Jochen Woessner, and Egill Hauksson Earthquake Monitoring in Southern California for Seventy-Seven Years (1932–2008) Bulletin of the Seismological Society of America, Apr 2010; 100: 423 - 446.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17934
Deposited By: Ruth Sustaita
Deposited On:12 Apr 2010 18:26
Last Modified:08 Nov 2021 23:40

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