Fault steps and the dynamic rupture process: 2-D numerical simulations of a spontaneously propagating shear fracture

Journal Article · Wed May 01 00:00:00 EDT 1991 · Geophysical Research Letters (American Geophysical Union); (United States)

DOI:https://doi.org/10.1029/91GL01061· OSTI ID:5511848

Harris, R A; Archuleta, R J ^[1]; Day, S M ^[2]

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1. Univ. of California, Santa Barbara (United States)
2. San Diego State Univ., CA (United States)

Fault steps may have controlled the sizes of the 1966 Parkfield, 1968 Borrego Mountain, 1979 Imperial Valley, 1979 Coyote Lake and the 1987 Superstition Hills earthquakes. This project investigates the effect of fault steps of various geometries on the dynamic rupture process. The authors have used a finite difference code to simulate spontaneous rupture propagation in two dimensions. They employ a slip-weakening fracture criterion as the condition for rupture propagation and examine how rupture on one plane initiates rupture on parallel fault planes. The geometry of the two parallel fault planes allows for stepover widths of 0.5 to 10.0 m and overlaps of {minus}5 to 5 km. Results demonstrate that the spontaneous rupture on the first fault segment continues to propagate onto the second fault segment for a range of geometries for both compressional and dilational fault steps. A major difference between the compressional and dilational cases is that a dilational step requires a longer time delay between the rupture front reaching the end of the first fault segment and initiating rupture on the second segment. Therefore this dynamic study implies that a compressional step will be jumped quickly, whereas a dilational step will cause a time delay leading to a lower apparent rupture velocity. The authors also find that the rupture is capable of jumping a wider dilational step than compressional step.

• OSTI ID: 5511848
• Journal Information: Geophysical Research Letters (American Geophysical Union); (United States), Vol. 18:5; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
EARTHQUAKES
ROCK MECHANICS
GEOLOGIC FAULTS
CRACK PROPAGATION
COMPRESSION
EARTHQUAKE MAGNITUDE
FINITE DIFFERENCE METHOD
GEOLOGIC FRACTURES
GEOLOGIC MODELS
GEOMETRY
MATHEMATICAL MODELS
PROCESS CONTROL
RUPTURES
SIMULATION
SLIP
TIME DELAY
TWO-DIMENSIONAL CALCULATIONS
CONTROL
FAILURES
GEOLOGIC STRUCTURES
ITERATIVE METHODS
MATHEMATICS
MECHANICS
NUMERICAL SOLUTION
SEISMIC EVENTS
580000* - Geosciences