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Overlapping fault planes of the 1971 San Fernando and 1994 Northridge, California earthquakes
Author(s) -
Mori Jim,
Wald David J.,
Wesson Robert L.
Publication year - 1995
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 - 10.1029/95gl00712
Subject(s) - aftershock , seismology , geology , fault plane , fault (geology) , plane (geometry) , compression (physics) , geometry , materials science , mathematics , composite material
Aftershocks of the 1971 San Fernando and 1994 Northridge earthquakes were relocated using a three‐dimensional velocity model that was derived from inverting P‐wave travel time data. The hypocenters show clear orientations of the dipping fault planes. The San Fernando aftershocks form a plane extending from a depth of 15 km to the surface, dipping toward the northeast at about 40°. The Northridge aftershocks delineate a fault extending from a depth of 18 km up to about 5 km, dipping toward the southwest at about 40°. In the region the aftershocks overlap in map view, the San Fernando plane cuts off the Northridge plane at a depth of 5 to 8 km, preventing it from reaching the surface. The similar but oppositely dipping fault planes suggest a pair of conjugate planes reflecting a horizontal northeast‐southwest compression.