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Paleoseismologic Evidence For Holocene Activity On The Pinto Mountain Fault, Twentynine Palms, California, Ana Maria Cadena

All Master's Theses

Excavations across the Pinto Mountain fault in Twentynine Palms, California exposed faulted strata across a 32-m wide zone. Trench wall exposures revealed clear evidence for five ground-rupturing events during the Holocene, and two additional events in the late Pleistocene. Optically stimulated luminescence ages from alluvial sediments suggest that the most recent event occurred between 1.7-2.9 ka B.P. and the penultimate event between 2.7-4.2 ka B.P.. Prior to the penultimate event, there were five ground-rupturing earthquakes on the eastern Pinto Mountain fault between 3.5-13.6 ka B.P.. The average recurrence interval since 13.3-13.6 ka B.P. is 1510-1680 years, and 1200-1500 years in …