Kenneth M. Cruikshank
1992 Landers Earthquake

Kenneth M. Cruikshank
1992 Landers Earthquake

Johnson, A.M., Fleming, R.W., Cruikshank, K.M., Martosudarmo, S.Y., Johnson, N.A., Johnson, K.M., and Wel, W., 1997. Analecta of Structures Formed During the 28 June 1992 Landers-Big Bear, California Earthquake Sequence. Including Maps of Shear Zones, Belts of Shear Zones, Tectonic Ridge, Duplex En Echelon Fault, Fault Elements, and Thrusts in Restraining Steps. U.S. Geological Survey Open-File Report 97-94.

Summary

Ground rupture that occurred during the 28 June 1992 Landers-Big Bear, California, earthquake sequence has provided an unusual opportunity to map structures that form near the ground surface during strike-slip faulting. The largest structure, which is illustrated in an index-scale map, is the Landers-Big Bear rotating block. This block is defined on the east by an arcuate rupture 80-90 km long consisting of en echelon, right-stepping right-lateral fault zones that change orientation from north to south. The entire 1992 fault rupture defines an arc of about 60° with a radius of 70-80 km centered near the San Andreas fault zone to the west. In 1992 the Landers-Big Bear block rotated counterclockwise relative to surrounding ground, and deformed internally Deformation within the rotating block may have caused the left-lateral earthquake sequence near Big Bear Lake.

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