Cross-fault triggering in the November 1987 Superstition Hills earthquake sequence, southern California

Journal Article · Wed Feb 01 04:00:00 EST 1989 · Geophysical Research Letters (American Geophysical Union); (USA)

DOI:https://doi.org/10.1029/GL016i002p00199· OSTI ID:5542324

Hudnut, K W; Pacheco, J ^[1]; Seeber, L ^[2]

---

1. Lamont-Doherty Geological Observatory, Palisades, NY (USA) Columbia University, New York, NY (USA)
2. Lamont-Doherty Geological Observatory, Palisades, NY (USA)

Two large strike-slip ruptures 11.4 hours apart occurred on intersecting, nearly orthogonal, vertical faults during the November 1987 Superstition Hills earthquake sequence in southern California. This sequence is the latest in a northwestward progression of earthquakes (1979, 1981, and 1987) rupturing a set of parallel left-lateral cross-faults that trend northeast between the Brawley seismic zone and Superstition Hills fault, a northwest trending main strand of the San Jacinto fault zone. The first large event (M{sub s} = 6.2) in the 1987 sequence ruptured the Elmore Ranch fault, a cross-fault that strikes northeasterly between the Brawley seismic zone and the Superstition Hills main fault. The second event (M{sub s} = 6.6) initiated its rupture at the intersection of the cross-fault and main fault and propagated towards the southeast along the main fault. The following hypotheses are advanced; (1) slip on the cross-fault locally decreased normal stress on the main fault, and triggered the main fault rupture after a delay; and (2) the delay was caused by fluid diffusion. It is inferred that the observed northwestward progression of ruptures on cross-faults may continue. The next cross-fault expected to rupture intersects both the San Andreas fault and the San Jacinto fault zone. The authors hypothesize that rupture of this cross-fault may trigger rupture on either of these main faults by a mechanism similar to that which occurred in the Superstition Hills earthquake sequence.

• OSTI ID: 5542324
• Journal Information: Geophysical Research Letters (American Geophysical Union); (USA), Journal Name: Geophysical Research Letters (American Geophysical Union); (USA) Vol. 16:2; ISSN 0094-8276; ISSN GPRLA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CALIFORNIA
DEVELOPED COUNTRIES
DIFFUSION
EARTHQUAKE MAGNITUDE
EARTHQUAKES
FAILURES
FEDERAL REGION IX
FLUIDS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
MAPS
MECHANICS
NORTH AMERICA
RESERVOIR FLUIDS
ROCK MECHANICS
RUPTURES
SEISMIC EVENTS
USA