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Investigation of nearfield postseismic slip following the M w 7.3 Landers earthquake sequence of 28 June 1992, California
Author(s) -
Sylvester Arthur Gibbs
Publication year - 1993
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 - 10.1029/93gl01059
Subject(s) - geology , trilateration , seismology , san andreas fault , slip (aerodynamics) , fault (geology) , geodesy , alluvium , strike slip tectonics , sequence (biology) , geomorphology , geometry , physics , mathematics , genetics , triangulation , biology , thermodynamics
Repeated precise surveys of six nearfield trilateration arrays reveal that minor horizontal displacements occurred across the several fault ruptures in the five months following the Landers earthquake sequence. The displacements range from 0±2 mm on the Camp Rock and Emerson faults, to 3±2 mm on the Landers fault, to 9plusmn;2 mm on the Johnson Valley fault, to 40±5 mm on the Eureka Peak fault, consistent in magnitude and duration with GPS and creepmeter measurements by other investigators. The relative lack of afterslip at all sites except across the Eureka Peak fault is probably due to the lack of a thick alluvial cover. Concomitant precise resurveys of level lines across the San Andreas fault in Coachella Valley and of a trilateration array at Durmid Hill, south easternmost San Andreas fault, failed to reveal vertical or horizontal displacements greater than the allowable uncertainty (<1 mm for leveling; 2 mm±2 ppm for trilateration). Therefore the Landers earthquake sequence did not perturb the San Andreas in any way that was evident from our measurements of near‐surface strain.