SEISMICITY AND GEOMETRY OF A 110-KM-LONG BLIND THRUST-FAULT .1. THE 1985 KETTLEMAN HILLS, CALIFORNIA, EARTHQUAKE

被引:98
作者
EKSTROM, G [1 ]
STEIN, RS [1 ]
EATON, JP [1 ]
EBERHARTPHILLIPS, D [1 ]
机构
[1] US GEOL SURVEY, MENLO PK, CA 94025 USA
关键词
D O I
10.1029/91JB02925
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
The August 4, 1985, Kettleman Hills earthquake was the third in a sequence of moderate shocks to occur beneath the northern half of a 110-km-long fold chain bounding the eastern California Coast Ranges. The 1982 M(W) = 5.4 New Idria, 1983 M(W) = 6.5 Coalinga, and 1985 M(W) = 6.1 Kettleman Hills events define a southward progression of seismic activity beneath the fold. We use teleseismic waveforms, geodetic modeling, hypocenters relocated in a three-dimensional velocity model, and subsurface structural data to investigate the Kettleman Hills earthquake. The main shock results from motion on a shallowly dipping thrust fault buried at approximately 10 km depth. Aftershocks and coseismic fault slip extend 20 km along the fold axis, nearly the full extent of the Kettleman Hills North Dome anticline. Aftershocks occur primarily several kilometers in front of the fault tip and in the core of the anticline. The main shock and several foreshocks occurred at a 2-km right step in the Quaternary fold axis, which also corresponds to the southern end of the 1983 Coalinga and northern end of the 1985 Kettleman Hills aftershock zones. From this we infer that the step in the fold is caused by an offset or tear in the underlying fault. The scalar seismic moment is 1.6 x 10(18) N m, consistent with the geodetic deformation, and the duration of rupture is 16 s, 3-4 times greater than for the average earthquake with this scalar moment. The slow rate of moment release provides an explanation for the low level of ground shaking and low local magnitude reported for the event. The peak of the geodetic uplift is located 5 km perpendicular to the Quaternary fold axis. We argue that the fault is propagating northeast into the undeformed San Joaquin Valley sediments and that the overlying fold is growing at about 0.5 mm/yr.
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页码:4843 / 4864
页数:22
相关论文
共 58 条
[41]  
RODGERS DA, 1981, THRUST NAPPE TECTONI, P65
[42]   HYDROLOGIC EFFECTS ON WATER LEVEL CHANGES ASSOCIATED WITH EPISODIC FAULT CREEP NEAR PARKFIELD, CALIFORNIA [J].
ROELOFFS, EA ;
BURFORD, SS ;
RILEY, FS ;
RECORDS, AW .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1989, 94 (B9) :12387-12402
[43]  
RUMPF WE, 1981, 16 FIG C MONTR
[44]  
SARNAWOJCICKI AM, 1991, GEOLOGY N AM K, V2, P117
[45]   STRESS AND SUBSIDENCE RESULTING FROM SUBSURFACE FLUID WITHDRAWAL IN THE EPICENTRAL REGION OF THE 1983 COALINGA EARTHQUAKE [J].
SEGALL, P .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1985, 90 (NB8) :6801-6816
[46]   HIDDEN EARTHQUAKES [J].
STEIN, RS ;
YEATS, RS .
SCIENTIFIC AMERICAN, 1989, 260 (06) :48-57
[47]   SEISMIC POTENTIAL REVEALED BY SURFACE FOLDING - 1983 COALINGA, CALIFORNIA, EARTHQUAKE [J].
STEIN, RS ;
KING, GCP .
SCIENCE, 1984, 224 (4651) :869-872
[48]  
STEIN RS, 1992, J GEO R-SOL, V97
[49]  
STOVER CW, 1991, US GEOL SURV B, V1954
[50]  
STOVER CW, 1983, SPEC PUBL CALIF DIV, V66, P1