- © 2007 by the Seismological Society of America
The Cerro Prieto geothermal field, considered an active developing rift basin, is located in the southern limits of the Salton Trough tectonic province. The tectonic activity along the Gulf of California–Salton Trough has created spreading centers linked through a set of transform faults. Such faults are characterized by right lateral motion obliquely oriented to the gulf axis, which produces a transtensional stress regime along the Pacific–North American plate boundary. In particular, the Cerro Prieto basin has developed between the major Cerro Prieto and Imperial right-stepping transform faults, which are part of the San Andreas–Gulf of California fault system (figure 1). Both faults are seismically active and have produced several magnitude 7 earthquakes. However, in the past decades only the Imperial fault has produced superficial ground breakage during earthquakes. This is in contrast to earthquake ruptures on the Cerro Prieto fault, which have not extended up to the ground surface, so this fault trace is not yet well-constrained.
The epicenter of the 24 May 2006 Mw 5.4 earthquake was located along the northern end of the Cerro Prieto fault. In a field survey performed after the earthquake, superficial fractures were clearly observed at short distances from the epicenter. Based on our field observations, we address the question of whether such fractures are evidence of rupture along the Cerro Prieto fault or are associated with a conjugate fault.
SEISMICITY AND FIELD OBSERVATIONS
On 24 May 2006 at 04:20 (UTC) …