HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) References Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by RICHTER, C. F. Articles by NORDQUIST, J. M. Search for Related Content GeoRef GeoRef Citation

The Desert Hot Springs earthquakes and their tectonic environment

CALIFORNIA INSTITUTE OF TECHNOLOGY,, PASADENA, CALIFORNIA

Abstract

The Desert Hot Springs earthquake of December 4, 1948, was one of the larger recorded earthquakes of southern California, and its aftershocks have continued into 1957. The assigned epicenter is W; origin time, 15:43:16.7 P.S.T.; magnitude 6 1/2. Arrival times at local and distant stations are consistent with existing travel-time curves, except for anomalous S – P intervals at very near-by temporary stations; these unexplained anomalies cannot be attributed to varying depth of focus.

Epicenters of the 72 aftershocks that have been accurately located are concentrated in a zone 18 km. long, parallel to the Mission Creek fault trace indicated by older scarps, but 5 km. north of it. Aftershock activity is markedly concentrated toward the two ends of this line. Location of the main shock suggests that fracturing started near the southeast end and progressed northwest-ward. The ground surface was not broken, except by landslides.

Offset of the line of seismic activity from the trace of the Mission Creek fault suggests that the fault plane dips north. This attitude is substantiated not only by field observations, but also by first motions at stations within 6° of the epicenter, which require a combination of thrust-slip and right lateral-slip on a fault dipping north less than 66°. Inasmuch as this fault is not parallel to regional San Andreas trend, such oblique displacement is reasonable and is consistent with the tectonic pattern of other faults in this region.

Five groups of earthquakes represent more than 85 per cent of the total strain release since 1933 in the 3,000 sq. km. area surrounding Desert Hot Springs. These earthquakes, in addition to the Desert Hot Springs shock, are: Morongo Valley (1947), Kitching Peak (1944), Covington Flat (1940), and San Gorgonio Mountain (1935); all are associated with known faults. The Morongo Valley earthquakes probably represent fracturing on the segment of the Mission Creek fault adjacent to that broken during the subsequent Desert Hot Springs shock.

This article has been cited by other articles:

				C. Nicholson Seismic behavior of the southern San Andreas fault zone in the northern Coachella Valley, California: Comparison of the 1948 and 1986 earthquake sequences Bulletin of the Seismological Society of America, October 1, 1996; 86(5): 1331 - 1349. [Abstract] [PDF]

				M. D. Petersen and S. G. Wesnousky Fault slip rates and earthquake histories for active faults in southern California Bulletin of the Seismological Society of America, October 1, 1994; 84(5): 1608 - 1649. [Abstract] [PDF]

				T. C. HANKS and A. C. JOHNSTON Common features of the excitation and propagation of strong ground motion for North American earthquakes Bulletin of the Seismological Society of America, February 1, 1992; 82(1): 1 - 23. [Abstract] [PDF]

				C. R. ALLEN Charles F. Richter: A personal tribute Bulletin of the Seismological Society of America, December 1, 1987; 77(6): 2234 - 2237. [PDF]

				L. M. JONES, L. K. HUTTON, D. D. GIVEN, and C. R. ALLEN The North Palm Springs, California, earthquake sequence of July 1986 Bulletin of the Seismological Society of America, December 1, 1986; 76(6): 1830 - 1837. [PDF]

				T. H. HEATON Tidal triggering of earthquakes Bulletin of the Seismological Society of America, December 1, 1982; 72(6A): 2181 - 2200. [Abstract] [PDF]

				S. J. GIBOWICZ Stress drop and aftershocks Bulletin of the Seismological Society of America, August 1, 1973; 63(4): 1433 - 1446. [Abstract] [PDF]

				J. N. BRUNE and C. R. ALLEN A micro-earthquake survey of the San Andreas fault system in southern California Bulletin of the Seismological Society of America, April 1, 1967; 57(2): 277 - 296. [Abstract] [PDF]

				C. R. ALLEN, P. ST. AMAND, C. F. RICHTER, and J. M. NORDQUIST Relationship between seismicity and geologic structure in the Southern California region Bulletin of the Seismological Society of America, August 1, 1965; 55(4): 753 - 797. [Abstract] [PDF]

				J. M. NORDQUIST A catalog of Southern California earthquakes, and associated electronic data processing programs Bulletin of the Seismological Society of America, June 1, 1964; 54(3): 1003 - 1011. [Abstract] [PDF]