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020    9781124095097 
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040    UMI|cUMI 
100 1  Sarmiento, Alexandra C 
245 10 Earthquake recurrence and modes of deformation in the 
       central and northern Walker Lane: Observations from 
       paleoseismic trenches across the Carson and Sierra Nevada 
       Range fronts 
300    142 p 
500    Source: Masters Abstracts International, Volume: 48-06, 
       page: 3569 
500    Adviser: Robert J. Watters 
502    Thesis (M.S.)--University of Nevada, Reno, 2010 
520    Observations acquired through the mapping of Quaternary 
       deposits, the measurement of fault scarps and the 
       excavation of two trenches along the Sierra Nevada 
       Mountain Range provide information bearing on the rate and
       style of deformation in the central and northern Walker 
       Lane. Active uplift along the eastern flank of the Sierra 
       Nevada Mountain Range is manifest through triangular 
       facets, oversteepened range fronts and scarps in young 
       alluvium at fan heads. Structural, stratigraphic and 
       pedogenic relations exposed in a trench in Antelope Valley
       (∼39.59°N latitude) record a three-event 
       earthquake history, including two Holocene surface 
       ruptures and third event of an older but unknown age. 
       Radiocarbon dating of bulk samples shows the most recent 
       and penultimate events occurred ∼1350 cal ybp and &
       sim;6250 cal ybp, respectively. These dates imply a late 
       Holocene average recurrence interval of ∼5000 years. 
       Division of the 3.6 m most recent offset by the average 
       recurrence interval yields a late Holocene slip rate of mm
       /yr. A second trench was excavated across the Carson Range
       front fault at the latitude of Reno, Nevada (∼39.4&
       deg;N), along a nearly continuous, ∼4 km long range 
       front scarp. The exposure revealed a sharp, planar, low-
       angle failure surface dipping 33° and coincident with 
       a bedding plane in the Hunter Creek formation. Slip along 
       the failure surface juxtaposes a massive alluvial package 
       against the Hunter Creek sandstone. The low-angle failure 
       plane invokes two interpretations of the driving force 
       behind the displacement: (1) mass wasting in a landslide; 
       and (2) slip along a seismogenic low-angle normal fault. A
       landslide origin for displacement is unfavorable based on 
       the length and continuity of the scarp on the surface and 
       the absence of landslide debris downslope. The preferred 
       low-angle normal fault interpretation is supported by 
       documented surface rupture along the fault ∼2 km south
       of the site and the observation of an exceptionally high 
       density zone of short discontinuous faults in the pediment
       outboard the range front that may be a manifestation of 
       the low-angle structure at depth. Previous paleoseismic 
       studies show the low-angle slip proposed here is not 
       representative of the entire Carson Range, and that is 
       likely restricted to a few kilometers. Lastly, structural,
       stratigraphic and pedogenic relations in the trench are 
       insufficient to elucidate an earthquake event history 
590    School code: 0139 
650  4 Geology 
650  4 Continental Dynamics 
690    0372 
690    0406 
710 2  University of Nevada, Reno 
773 0  |tMasters Abstracts International|g48-06 
856 40 |uhttp://pqdd.sinica.edu.tw/twdaoapp/servlet/