EARTHQUAKE MAGNITUDE AND RECURRENCE FROM SCARP MORPHOLOGY, EUREKA VALLEY FAULT ZONE, EASTERN CALIFORNIA

The normal-oblique Eureka Valley fault zone (EVFZ) of eastern California (western Basin and Range) is the source of a 1993 earthquake (Mw 6.1). Geodetic models infer that the northeast-striking EVFZ is an important structure that transfers regional slip from the Owens Valley fault zone to the Fish Lake Valley fault zone with a slip rate of 3-3.5 mm/year. Imagery and regional mapping shows the EVFZ as discontinuous segments offsetting Quaternary deposits along the west side of the Last Chance Range; however, limited and insignificant ground rupture was reported after the 1993 earthquake with no reported geologically measured slip rate. In the southern Eureka Valley (37.07242N; 117.63916W) Quaternary landslide and alluvial fan deposits are cut by apparently normal fault scarps. In this study, we will present geologic mapping and scarp profiles that document the offset of these deposits by the EVFZ. Ages for these deposits will be estimated by correlation to geomorphically similar deposits in the region. Event ages will be modeled using methods developed by Nash (1984). This study will provide an initial assessment of geologic slip rates for the EVFZ that will be compared to the geodetic slip rates.