Investigation of a method for determining stress accumulation at depth—II

1969 ◽  
Vol 59 (1) ◽  
pp. 43-58
Author(s):  
Joseph D. Eisler
Keyword(s):  
Field Experiments ◽  
San Andreas Fault ◽  
Body Waves ◽  
Travel Times ◽  
Compressional Waves ◽  
San Andreas ◽  
Path Lengths ◽  
Stress Accumulation

Abstract The second of two seismic field experiments designed to study the precision with which the arrival of compressional body waves could be timed over paths up to 42 km in length was performed seven months after the first at the same location in the Gabilan Range near Salinas, California. Results of the second experiment show that the timing of the compressional waves could be carried out to the same order of precision as in the first experiment, i.e., to ±1 msec. In addition, the travel times over certain path lengths increased by about 6 msec within the intervening period. This observation is discussed in terms of the possible release of stress at depth in the region adjacent to the San Andreas Fault.

Directivity in the high-frequency radiation of small earthquakes

1978 ◽  
Vol 68 (5) ◽  
pp. 1253-1263
Author(s):  
W. H. Bakun ◽  
R. M. Stewart ◽  
C. G. Bufe
Keyword(s):  
High Frequency ◽  
Fault Plane ◽  
San Andreas Fault ◽  
Body Waves ◽  
Rupture Propagation ◽  
Central California ◽  
Hypocenter Location ◽  
San Andreas ◽  
Road Section ◽  
Frequency Radiation

abstract On December 12, 1972 at 0351 and 0355 GMT, two earthquakes with magnitudes equal to 3.0 and 2.8, respectively, occurred on the Cienega Road section of the San Andreas fault in central California. The two events have the same hypocenter location and fault-plane soultion. Observed seismograms for these two events at 28 stations within about 65 km of and surrounding the epicenters are systematically different in a pattern that is consistent with different directions of rupture expansion for the two events. The 0351 GMT event preferentially radiated high-frequency (f ⪚ 10 Hz) body waves to the southeast consistent with unilateral rupture propagation toward the southeast while the 0355 GMT event rupture expanded more toward the northwest.

An elastostatic model of stress accumulation on the San Andreas fault

1976 ◽  
Vol 349 (1658) ◽  
pp. 319-341 ◽  
Keyword(s):  
Strain Energy ◽  
San Andreas Fault ◽  
Great Earthquake ◽  
Stress And Strain ◽  
San Andreas ◽  
Plate Velocity ◽  
The Pacific ◽  
Strain Components ◽  
Distribution Of Stress ◽  
Stress Accumulation

Earthquakes on the San Andreas fault in California are due to lateral motion between the Pacific and Americas plates. Some sections of the fault are locked (to a fraction of their depth) between major earthquakes while others are free-sliding. We model this problem by considering two semi-infinite plates sliding past each other. Near the fault an inner solution in the vertical cross-plane is obtained. If the length of the locked sections is large compared with the thickness of the plates an outer solution exists in which the stress and strain components are constant across the plates. Such solutions are obtained for (i) a single locked section, (ii) two locked sections separated by a central crack. The inner and outer solutions are asymptotically matched, and the results used to predict the distribution of stress and strain near the fault. The creep velocities on the freesliding sections are shown to be a fraction of the relative plate velocity. When a great earthquake occurs on one locked section it appears that a significant fraction of the relieved stress is transferred to each adjacent locked section. An expression is obtained for the strain energy so released.

The focus of the 1906 California earthquake

1968 ◽  
Vol 58 (1) ◽  
pp. 457-471
Author(s):  
Bruce A. Bolt
Keyword(s):  
San Francisco ◽  
San Andreas Fault ◽  
Travel Times ◽  
Santa Cruz ◽  
San Andreas ◽  
Lines Of Evidence

abstract The location of the 1906 California earthquake is reexamined using both the P and S recordings at teleseismic distances and the local observations. Analysis of the observed travel times using modern empirical tables rules out a focus of the principal shock south of the Santa Cruz Mountains or north of Point Arena. By inter-comparison with the measurements from the 1957 San Francisco earthquake, it is demonstrated that the lines of evidence are slightly more favorable to a principal focus near that of the 1957 California shock (37°40′N, 122°29′W) with t0 = 13h12m21s than to Reid's focus near Olema, although the latter is not precluded. There is no evidence from the travel times against the hypothesis that the first rupture was associated with the San Andreas fault and occurred within the crust. The analysis confirms that the rupture was of the (perhaps unusual) bilateral type. Calculations which confirm the contentious magnitude of 814 are set down.

The San Andreas Fault

1993 ◽  
Author(s):  
Sandra S. Schulz ◽  
Robert E. Wallace
Keyword(s):  
San Andreas Fault ◽  
San Andreas
Sign in / Sign up

Export Citation Format

Share Document