scholarly journals Behavior of Repeating Earthquake Sequences in Central California and the Implications for Subsurface Fault Creep

2008 ◽  
Vol 98 (1) ◽  
pp. 52-65 ◽  
Author(s):  
D. C. Templeton ◽  
R. M. Nadeau ◽  
R. Burgmann
Keyword(s):  
Fault Creep ◽  
Central California ◽  
Repeating Earthquake ◽  
Earthquake Sequences

Long-term fault creep observations in central California

1982 ◽  
Vol 87 (B8) ◽  
pp. 6977-6982 ◽  
Author(s):  
Sandra S. Schulz ◽  
Gerald M. Mavko ◽  
Robert O. Burford ◽  
William D. Stuart
Keyword(s):  
Fault Creep ◽  
Central California

A one-parameter expression of seismicity patterns in space and time

1984 ◽  
Vol 74 (6) ◽  
pp. 2559-2576
Author(s):  
Shozo Matsumura
Keyword(s):  
Distribution Function ◽  
Weibull Distribution ◽  
Seismicity Patterns ◽  
Objective Criterion ◽  
Central California ◽  
Seismicity Pattern ◽  
Space And Time ◽  
San Andreas ◽  
Earthquake Sequences ◽  
The U.S

Abstract A technique to express changes in seismicity patterns by means of an objective criterion has been investigated. A parameter v2=(Δ¯)2/Δ¯2, where Δ is the distance between two adjacent earthquakes in space and time, was derived on the basis of the Weibull distribution function. This parameter can be related to an apparent interaction in the earthquake sequences and used to monitor changes of the seismicity patterns which may reflect the state of the crustal stress. The patterns are classified as regular, completely random, and clustered according to the value of v2. The technique was applied to the U.S. Geological Survey microearthquake catalog for central California. A total of 9740 earthquakes (M ≧ 1.5) was selected from along the 250-km-long creeping zone of the San Andreas and Calaveras faults for the period 1971 to 1981. The seismicity pattern was found to be generally a combination of highly clustered ones overlapped with a background, which was characterized as almost random or slightly clustered.

A Discussion on the measurement and interpretation of changes of strain in the Earth - Kinematics of fault creep

1973 ◽  
Vol 274 (1239) ◽  
pp. 355-360 ◽  
Keyword(s):  
Seismic Waves ◽  
Fault System ◽  
Creep Process ◽  
Fault Creep ◽  
Central California ◽  
Rupture Length ◽  
San Andreas ◽  
The Earth ◽  
San Andreas Fault System ◽  
Failure Propagation

Fault slip and strain during fault-creep episodes are continuously recorded by a dense network of creepmeters deployed along several major traces of the San Andreas fault system in central California. These data are analysed on the basis of theoretical faulting models to delineate the kinematics of the fault-creep process. The results indicate that fault creep is a failure propagation phenomenon, kinematically similar to seismic faulting, but with very low characteristic rates. The speed of creep propagation is not constant and is of the order of 10 km/day or less. The maximum slip velocity usually ranges from 0.1 to 10 p.m/s. Both of these are five or more orders of magnitude smaller than the corresponding rates of seismic faulting. The slowness in particle motion can account for the ineffectiveness of the creep process in exciting observable seismic waves. However, the tectonic strain released by a creep event may be sizable. The largest event recorded so far has a rupture length of 6 km and a maximum offset of 9 mm, comparable to similar parameters of a shallow earthquake of magnitude 4.7.

Fault creep in central California

Eos ◽  
1969 ◽  
Vol 50 (5) ◽  
pp. 385
Author(s):  
Don Tocher
Keyword(s):  
Fault Creep ◽  
Central California

Seismological studies at Parkfield IV: Variations in controlled-source waveform parameters and their correlation with seismicity, 1987 to 1995

1997 ◽  
Vol 87 (1) ◽  
pp. 39-49 ◽  
Author(s):  
E. Karageorgi ◽  
T. V. McEvilly ◽  
R. Clymer
Keyword(s):  
Wave Field ◽  
Travel Time ◽  
Fault Zone ◽  
Water Levels ◽  
Deep Penetration ◽  
Fault Creep ◽  
Data Set ◽  
Spectral Content ◽  
S Waves ◽  
Earthquake Sequences

Abstract Since June 1987 at Parkfield, California, the 10-station borehole network of three-component sensors has been illuminated 52 times using a shear-wave vibrator in three orientations at up to eight source points, in a search for temporal changes in elastic wave P and S velocities, anisotropy, or attenuation. The monitoring interval includes the beginning and end of a severe 3-yr drought and four earthquake sequences, two of which produced the only A-level alerts to date in the Parkfield Prediction Experiment. A comprehensive study of the entire data set reveals a progressive travel-time advance in the coda of S waves propagating in a localized region southeast of Middle Mountain. The anomalous wave field exhibits high apparent velocities, suggesting deep penetration of the fault zone, although similar changes are not seen in waveforms from repeating similar microearthquakes. Accompanying the changes in travel time were systematic variations in spectral content and polarization of the same segments of the wave field. These variations correlate well in time and space with significant features of seismicity, fault creep, and water levels at Parkfield. A preferred mechanism for the phenomenon is changing hydrologic conditions along the affected stretch of the fault zone, possibly deformation-induced, that perturb the shallow-propagating S coda in the upper few hundred meters of section.

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