Equivalent strike-slip earthquake cycles in half-space and lithosphere-asthenosphere Earth models

Journal Article · Tue Apr 10 00:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB04p04873· OSTI ID:5014998

Savage, J C ^[1]

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1. Geological Survey, Menlo Park, CA (United States)

By virtue of the images used in the dislocation solution, the deformation at the free surface produced throughout the earthquake cycle by slippage on a long strike-slip fault in an Earth model consisting of an elastic plate (lithosphere) overlying a visoelastic half-space (asthenosphere) can be duplicated by prescribed slip on a vertical fault embedded in an elastic half-space. For the case in which each earthquake ruptures the entire lithosphere (thickness H), the half-space equivalent slip rate is as follows: Depth interval 0-H, slip identical to that in lithosphere-asthenosphere model (i.e., abrupt coseismic slip and no subsequent slip); depth interval (2n {minus} 1) H to (2n + 1) H (n = 1,2,...), slip rate uniform in space and dependent upon time as F{sub n}(t) exp ({minus}t/{tau}) where F{sub n} is a (n {minus} 1) degree polynomial in t, {tau} is twice the asthenosphere relaxation time, and t is measured from the instant after the preceding earthquake. The slip rate averaged over the seismic cycle in each depth interval equals the secular rate of relative plate motion. The surface deformation due to the earthquake cycle in the lithosphere-asthenosphere model can be calculated very simply from the half-space model with time-dependent slip in the two depth intervals H-3H and 3H-5H, and uniform slip at a rate equal to the secular relative plate velocity below depth 5H. Inversion of 1973-1988 geodetic measurements of deformation across the segment of the San Andrea fault in the Transverse Ranges north of Los Angeles for the half-space equivalent slip distribution suggests no significant slip on the fault above 30 km and a uniform slip rate of 36 mm/yr below 30 km.

• OSTI ID: 5014998
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:B4; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
EARTHQUAKES
GEOLOGIC MODELS
GEOLOGIC FAULTS
SLIP
DATA PROCESSING
DEFORMATION
DEPTH
ELASTICITY
EQUATIONS
GEODETIC SURVEYS
RELAXATION TIME
ROCK MECHANICS
TIME DEPENDENCE
DIMENSIONS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
MECHANICAL PROPERTIES
MECHANICS
PROCESSING
SEISMIC EVENTS
SURVEYS
TENSILE PROPERTIES
580000* - Geosciences