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Evidence for weak oceanic transform faults
Author(s) -
Behn Mark D.,
Lin Jian,
Zuber Maria T.
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl015612
Subject(s) - transform fault , geology , seismology , ridge , shear (geology) , mid ocean ridge , slow earthquake , series (stratigraphy) , fault (geology) , extensional definition , tectonics , petrology , subduction , paleontology , interplate earthquake , basalt
We present the results of a series of 3‐D boundary element calculations to investigate the effects of oceanic transform faults on stress state and fault development at adjacent mid‐ocean ridge spreading centers. We find that the time‐averaged strength of transform faults is low, and that on time scales longer than a typical earthquake cycle transform faults behave as zones of significant weakness. Specifically, mechanical coupling of only ∼5% best explains the observed patterns of strike‐slip and oblique normal faulting near a ridge‐transform intersection. On time scales shorter than a typical earthquake cycle, transient “locked” periods can produce anomalous reverse faulting similar to that observed at the inside corner (IC) of several slow‐spreading ridge segments. Furthermore, we predict that extensional stresses will be suppressed at the IC due to the shear along the transform resisting ridge‐normal extension. This implies that an alternative mechanism is necessary to explain the preferential normal fault growth and enhanced microseismicity observed at many ICs.