Localized and distributed creep along the southern San Andreas Fault

TitleLocalized and distributed creep along the southern San Andreas Fault
Publication TypeJournal Article
Year of Publication2014
AuthorsLindsey EO, Fialko Y, Bock Y, Sandwell DT, Bilham R.
JournalJournal of Geophysical Research-Solid Earth
Date Published2014/10
Type of ArticleArticle
ISBN Number2169-9313
Accession NumberWOS:000345368500031
Keywords1999 hector mine; central california; conditions; creep; fault; global positioning system; hayward fault; hydrothermal; inelastic; InSAR; mode-ii conditions; north anatolian fault; off-fault deformation; San Andreas Fault; strike-slip faults; synthetic-aperture radar; triggered surface slips; zone

We investigate the spatial pattern of surface creep and off-fault deformation along the southern segment of the San Andreas Fault using a combination of multiple interferometric synthetic aperture radar viewing geometries and survey-mode GPS occupations of a dense array crossing the fault. Radar observations from Envisat during the period 2003-2010 were used to separate the pattern of horizontal and vertical motion, providing a high-resolution image of uplift and shallow creep along the fault trace. The data reveal pervasive shallow creep along the southernmost 50 km of the fault. Creep is localized on a well-defined fault trace only in the Mecca Hills and Durmid Hill areas, while elsewhere creep appears to be distributed over a 1-2 km wide zone surrounding the fault. The degree of strain localization is correlated with variations in the local fault strike. Using a two-dimensional boundary element model, we show that stresses resulting from slip on a curved fault can promote or inhibit inelastic failure within the fault zone in a pattern matching the observations. The occurrence of shallow, localized interseismic fault creep within mature fault zones may thus be partly controlled by the local fault geometry and normal stress, with implications for models of fault zone evolution, shallow coseismic slip deficit, and geologic estimates of long-term slip rates. Key PointsShallow creep is pervasive along the southernmost 50 km of the San Andreas FaultCreep is localized only along transpressional fault segmentsIn transtensional areas, creep is distributed over a 1-2 km wide fault zone

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