Characterizing the Geometry and Seismotectonics of the Hilton Creek Fault System

Kyle P. Macy, Amber K. Lacy, Jason De Cristofaro, & Jascha Polet

Published August 15, 2016, SCEC Contribution #6794, 2016 SCEC Annual Meeting Poster #223

The Hilton Creek Fault System, in the Eastern Sierra Nevada, is characterized as a single NW-striking, NE-dipping, normal fault from Davis Lake to the southern rim of the Long Valley Caldera. Within the Caldera, the fault splays into multiple, parallel, subsidiary faults that spread across the Caldera floor toward the resurgent dome. Historically low seismicity in the area increased in May of 1980, after the occurrence of 4 large earthquakes. In the following decades, a series of earthquake swarms occurred throughout the area, many of which were on or near the Hilton Creek Fault System. Small vertical offsets have been associated with these events

We are conducting an interdisciplinary geophysical study of the Hilton Creek Fault System to delineate the fault splays within the caldera and compare and contrast the seismic behavior of those fault splays in the north, with that of the southern part of the Hilton Creek Fault System. Our investigation will include the generation of maps of the variation in b-values along different portions of the fault, ground-based magnetic field measurements, high-resolution total station elevation profiles, structure-from-motion derived topography, and an analysis of earthquake focal mechanisms. Topographic profiles of approximately 1 km in length, produced from total station measurements, show at least three distinct fault splays within the caldera with vertical offsets between 0.5 to 1 m. More detailed topographic mapping through structure-from-motion techniques is planned in the near future and is expected to highlight the full length of these splays. We will show maps of b-values, magnetic anomalies, topography, various models of the Hilton Creek Fault System and cross-sections through focal mechanism and earthquake catalogs, with the main goal of integrating these observations into a single fault geometry model.

Key Words
Earthquake, Seismology, Fault, Fault Splays, Caldera, Long Valley, Hilton Creek, Tectonics, Seismotectonics, Magnetics, Topography, Earthquake Statistics, Geodesy,

Macy, K. P., Lacy, A. K., De Cristofaro, J., & Polet, J. (2016, 08). Characterizing the Geometry and Seismotectonics of the Hilton Creek Fault System. Poster Presentation at 2016 SCEC Annual Meeting.

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