Document Type

Thesis

Date of Degree Completion

Spring 2016

Degree Name

Master of Science (MS)

Department

Geological Sciences

Committee Chair

Anne Egger

Second Committee Member

Walter Szeliga

Third Committee Member

Lisa Ely

Abstract

Using mapped paleoshoreline features with high-resolution topographic data and obtained radiocarbon dates on paleoshoreline tufas, I documented precise fault offsets of dated features over the last 25 ka along the Surprise Valley Fault (SVF). Fault offset measured in three lake sections within Surprise Valley ranged from 3.6 m in the southern section to 14.4 m in the central section. The offset paleoshorelines are dated to the late Pleistocene (<22 >ka) and were formed during the latest impoundment of pluvial Lake Surprise since the last glacial maximum. Slip rates vary along strike, assuming a fault dip of 68° with 0.25 ± 0.02 mm/yr in the northern section, 1.07 ± 0.10 mm/yr in the central section, and 0.36 ± 0.04 mm/yr in the southern lake section. Potential field modeling of profiles drawn through detailed, gridded gravity and magnetic data, suggest that the surficial scarps continue at depth, where they may accommodate greater offset. These results refine the time-averaged slip rate along the SVF and show variability spatially and temporally, allowing for correlations with changes in paleolake levels. This study suggest iv complex relation between pluvial lakes and their proximal faults that show that the lake likely influenced earthquake recurrence and slip rate along the SVF.

plate_v5.pdf (6901 kB)
Appendix A - Plate 1 - Surprise Valley with mapped paleoshorelines

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