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Geologic context of geodetic data across a Basin and Range normal fault, Crescent Valley, Nevada

Friedrich, A. M. and Lee, J. and Wernicke, B. P. and Sieh, K. (2004) Geologic context of geodetic data across a Basin and Range normal fault, Crescent Valley, Nevada. Tectonics, 23 (2). Art. No. TC2015. ISSN 0278-7407. http://resolver.caltech.edu/CaltechAUTHORS:20101123-092252306

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Abstract

Geodetic strain and late Quaternary faulting in the Basin and Range province is distributed over a region much wider than historic seismicity, which is localized near the margins of the province. In the relatively aseismic interior, both the magnitude and direction of geodetic strain may be inconsistent with the Holocene faulting record. We document the best example of such a disagreement across the NE striking, ~55° NW dipping Crescent normal fault, where a NW oriented, 70 km geodetic baseline records contemporary shortening of ~2 mm/yr orthogonal to the fault trace. In contrast, our geomorphic, paleoseismic, and geochronologic analyses of the Crescent fault suggest that a large extensional rupture occurred during the late Holocene epoch. An excavation across the fault at Fourmile Canyon reveals that the most recent event occurred at 2.8 ± 0.1 ka, with net vertical tectonic displacement of 4.6 ± 0.4 m at this location, corresponding to the release of ~3 m of accumulated NW-SE extension. Measured alluvial scarp profiles suggest a minimum rupture length of 30 km along the range front for the event, implying a moment magnitude M_w of at least 6.6. No prior event occurred between ~2.8 ka and ~6.4 ± 0.1 ka, the ^(14)C calender age of strata near the base of the exposed section. Assuming typical slip rates for Basin and Range faults (~0.3 mm/yr), these results imply that up to one third, or ~1 m, of the extensional strain released in the previous earthquake could have reaccumulated across the fault since ~2.8 ka. However, the contemporary shortening implies that the fault is unloading due to a transient process, whose duration is limited to between 6 years (geodetic recording time) and 2.8 ka (the age of the most recent event). These results emphasize the importance of providing accurate geologic data on the timescale of the earthquake cycle in order to evaluate geodetic measurements.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/2003TC001528 DOIUNSPECIFIED
http://www.agu.org/pubs/crossref/2004/2003TC001528.shtmlPublisherUNSPECIFIED
Additional Information:© 2004 American Geophysical Union. Received 31 March 2003; revised 16 October 2003; accepted 18 November 2003; published 16 April 2004. This study was supported by NSF grants EAR 99-03366 and EAR-00-01209 awarded to B. Wernicke and K. Sieh, and grant EAR-9902968 awarded to J. Lee. A. Friedrich acknowledges additional financial support from the University of Potsdam. We thank M. Jackson and R. Bruhn for providing surveying equipment, and B. Phillibosian, R. Heermance, and J. Liu for valuable assistance in the field. We benefited from reviews by D. Hindle, S. Mc Gill, and R. Hetzel and discussions with J. Bell, J. Caskey, C. DePolo, K. Haller, M. Machette, A. Ramelli, and S. Wesnousky on Basin and Range paleoseismology. Auxiliary material for this article contains excavation logs, fault scarp measurements along the Cortez range front, and stratigraphic descriptions of unit exposed in the excavation on the north side of Fourmile Canyon.
Group:Caltech Tectonics Observatory
Funders:
Funding AgencyGrant Number
NSFEAR 99-03366
NSFEAR-00-01209
NSFEAR-9902968
University of PotsdamUNSPECIFIED
Subject Keywords:Geodesy and Gravity: Crustal movements—intraplate; Seismology: Paleoseismology; Tectonophysics: Continental tectonics—extensional; Tectonophysics: Dynamics, seismotectonics
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Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory61
Record Number:CaltechAUTHORS:20101123-092252306
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20101123-092252306
Official Citation:Friedrich, A. M., J. Lee, B. P. Wernicke, and K. Sieh (2004), Geologic context of geodetic data across a Basin and Range normal fault, Crescent Valley, Nevada, Tectonics, 23, TC2015, doi:10.1029/2003TC001528
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20970
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:24 Nov 2010 22:53
Last Modified:26 Dec 2012 12:40

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