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Geodetic evidence for a buried fault segment at the Southern end of the San Jacinto Fault Zone

Fecha 2017-11-17, 13:30:00 hrs
Lugar: Audiovisual de Ciencias de la Tierra
Ponente(s): C.Dra. Ekaterina Tymofyeyeva
Scripps Institution of Oceanography
Resumen:  The San Jacinto Fault is the most seismically active fault in Southern California. It accommodates a large fraction of the relative motion between the North American and Pacific plates, and represents a significant seismic hazard. At its southern end, the San Jacinto Fault (SJF) splits into several active strands, including the Clark fault, the Buck Ridge fault, and the Coyote Creek fault. The Coyote Creek segment is considered to be the most active strand of the San Jacinto Fault system. However, geodetic and geologic studies have identified anomalous deformation to the east of the Coyote Creek Fault, indicating the possibility of a buried continuation of the Clark Fault to the south. We present new InSAR and GPS measurements that confirm high strain rates east of the Coyote Creek fault, and suggest that the buried southern portion of the Clark fault may accommodate a significant portion of the deformation on the southern end of the SJF.

We have developed a method to reduce the errors due to the atmospheric noise in InSAR data, allowing for greater accuracy in investigating low-amplitude interseismic crustal deformation. We apply our method to derive maps of horizontal and vertical average velocities by combining data from ascending and descending satellite orbits with the azimuth of the horizontal component of continuous and campaign GPS velocities. The resulting high-resolution horizontal surface velocities are differentiated to obtain a map of maximum shear strain rate. Joint inversions of InSAR and GPS data suggest that the hypothesized buried segment of the Clark fault and the Coyote Creek fault have slip rates of 13 mm/yr and 5 mm/yr, respectively. The buried southern segment of the Clark fault therefore appears to be the main active strand of the SJF, posing a currently unrecognized seismic hazard.


Ekaterina Tymofyeyeva (B.S.09, M.S.13) was born in Odessa, Ukraine. She received a B.S. degree in Physics from The College of New Jersey in 2009, and an M.S. degree in Earth Science from the University of California San Diego in 2013.

She is currently a PhD candidate at the Scripps Institution of Oceanography, UCSD. Her research interests include applications of Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) measurements to the study of crustal deformation related to tectonics.

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