A high-precision MT study of the mid and lower crustal San Andreas fault zone. Final report, April 1, 1994--March 31, 1996

1997 ◽  
Author(s):  
R.L. Mackie ◽  
D.W. Livelybrooks ◽  
T.R. Madden ◽  
J.C. Larsen
Keyword(s):  
Fault Zone ◽  
High Precision ◽  
San Andreas Fault ◽  
Final Report ◽  
San Andreas ◽  
Lower Crustal

Continuous borehole strain in the San Andreas fault zone before, during, and after the 28 June 1992, MW 7.3 Landers, California, earthquake

1994 ◽  
Vol 84 (3) ◽  
pp. 799-805 ◽  
Author(s):  
M. J. S. Johnston ◽  
A. T. Linde ◽  
D. C. Agnew
Keyword(s):  
Fault Zone ◽  
High Precision ◽  
Seismic Data ◽  
San Andreas Fault ◽  
Fault Geometry ◽  
Landers Earthquake ◽  
San Andreas ◽  
Strain Data ◽  
Local Slip ◽  
Ground Displacements

Abstract High-precision strain was observed with a borehole dilational strainmeter in the Devil's Punchbowl during the 11:58 UT 28 June 1992 MW 7.3 Landers earthquake and the large Big Bear aftershock (MW 6.3). The strainmeter is installed at a depth of 176 m in the fault zone approximately midway between the surface traces of the San Andreas and Punchbowl faults and is about 100 km from the 85-km-long Landers rupture. We have questioned whether unusual amplified strains indicating precursive slip or high fault compliance occurred on the faults ruptured by the Landers earthquake, or in the San Andreas fault zone before and during the earthquake, whether static offsets for both the Landers and Big Bear earthquakes agree with expectation from geodetic and seismologic models of the ruptures and with observations from a nearby two-color geodimeter network, and whether postseismic behavior indicated continued slip on the Landers rupture or local triggered slip on the San Andreas. We show that the strain observed during the earthquake at this instrument shows no apparent amplification effects. There are no indications of precursive strain in these strain data due to either local slip on the San Andreas or precursive slip on the eventual Landers rupture. The observations are generally consistent with models of the earthquake in which fault geometry and slip have the same form as that determined by either inversion of the seismic data or inversion of geodetically determined ground displacements produced by the earthquake. Finally, there are some indications of minor postseismic behavior, particularly during the month following the earthquake.

Water-level fluctuations and earthquakes on the San Andreas fault zone

Geology ◽  
1975 ◽  
Vol 3 (8) ◽  
pp. 437 ◽  
Author(s):  
Robert L. Kovach ◽  
Amos Nur ◽  
Robert L. Wesson ◽  
Russell Robinson
Keyword(s):  
Water Level ◽  
Fault Zone ◽  
San Andreas Fault ◽  
Water Level Fluctuations ◽  
San Andreas

Interpretation of seismic reflection profiling data for the structure of the San Andreas fault zone

1983 ◽  
Vol 73 (6A) ◽  
pp. 1701-1720
Author(s):  
R. Feng ◽  
T. V. McEvilly
Keyword(s):  
Fault Zone ◽  
Seismic Reflection ◽  
San Andreas Fault ◽  
Velocity Model ◽  
Seismic Reflection Profile ◽  
Lateral Velocity ◽  
Zone Structure ◽  
Ray Method ◽  
Velocity Change ◽  
San Andreas

Abstract A seismic reflection profile crossing the San Andreas fault zone in central California was conducted in 1978. Results are complicated by the extreme lateral heterogeneity and low velocities in the fault zone. Other evidence for severe lateral velocity change across the fault zone lies in hypocenter bias and nodal plane distortion for earthquakes on the fault. Conventional interpretation and processing methods for reflection data are hard-pressed in this situation. Using the inverse ray method of May and Covey (1981), with an initial model derived from a variety of data and the impedance contrasts inferred from the preserved amplitude stacked section, an iterative inversion process yields a velocity model which, while clearly nonunique, is consistent with the various lines of evidence on the fault zone structure.

High-Resolution Seismic Images and Seismic Velocities of the San Andreas Fault Zone at Burro Flats, Southern California

2008 ◽  
Vol 98 (6) ◽  
pp. 2948-2961 ◽  
Author(s):  
C. C. Tsai ◽  
R. D. Catchings ◽  
M. R. Goldman ◽  
M. J. Rymer ◽  
P. Schnurle ◽  
...  
Keyword(s):  
High Resolution ◽  
Fault Zone ◽  
Southern California ◽  
San Andreas Fault ◽  
Seismic Velocities ◽  
San Andreas ◽  
Seismic Images

Low-velocity damaged structure of the San Andreas Fault at Parkfield from fault zone trapped waves

2004 ◽  
Vol 31 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Yong-Gang Li ◽  
John E. Vidale ◽  
Elizabeth S. Cochran
Keyword(s):  
Fault Zone ◽  
San Andreas Fault ◽  
Trapped Waves ◽  
Low Velocity ◽  
San Andreas

DETAIL GRAVITY PROFILE ACROSS SAN ANDREAS FAULT ZONE

Geophysics ◽  
1967 ◽  
Vol 32 (2) ◽  
pp. 297-301 ◽  
Author(s):  
S. N. Domenico
Keyword(s):  
Fault Zone ◽  
Mojave Desert ◽  
San Andreas Fault ◽  
Surface Expression ◽  
Fault Zones ◽  
Rock Masses ◽  
San Andreas ◽  
Major Fault ◽  
Reduced Density ◽  
Gravity Profile

A gravity profile was obtained from closely spaced readings along a traverse approximately nine miles in length across the San Andreas fault zone immediately south of Palmdale, California in the western Mojave Desert. Corrected gravity values show a slight but distinctive minimum associated with the fault zone which may be attributed to the reduced density of the shattered rock masses in the fault zone. The existence of this minimum suggests that major fault zones may be traced across terrain, on which surface expression of the fault does not exist, by successive profiles across the suspected position of the fault zone.

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