As part of regional studies of paleoseismology in the northern Great Basin, we
are studying selected major extensional Quaternary faults in a traverse
from Reno, Nev., to Salt Lake City, Utah, between latitudes 39° and 41°
N. In 2001, we trenched the southern part of the Clan Alpine fault (CAF)
about 2 km northwest of the Alpine Ranch (see fig. 1). The fault separates
the Edwards Creek Valley (on the east) from the impressive front of the
uplifted Clan Alpine Mountains (on the west); faceted spurs along the
front suggest substantial Quaternary movement along the CAF (dePolo,
1998). Based on the tectonic geomorphology of the mountain front, dePolo
(1998) estimated a long-term slip rate of 0.15 mm/yr for the CAF. Conversely,
conspicuous fault scarps exist along only part of the range front, suggesting
that little movement has occurred on the CAF in late Quaternary time.
The purpose of this map product is to present stratigraphic, geomorphic, and
structural evidence for interpreting the late Quaternary movement history
of the CAF. The interpretive data will be presented elsewhere, pending
results of further dating studies. Nevertheless, the stratigraphic relations
shown on this map demonstrate two latest Quaternary surface-faulting
earthquakes in the past 30 k.y., and suggest that latest Quaternary slip
rates near the southern end of the fault zone are slower than previously
suggested for the whole fault zone.
This product is for sale at Information
Services, U.S. Geological Survey (1-888-ASK-USGS).
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1U.S. Geological Survey, Denver, Colorado;
2University of Montana, Bozeman, Montana;
3University of Hiroshima, Hiroshima, Japan
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| Posted August 2005 |
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