Date Available

11-4-2016

Year of Publication

2016

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Arts and Sciences

Department/School/Program

Earth and Environmental Sciences (Geology)

First Advisor

Dr. Sean Bemis

Abstract

The Denali fault (DF) in south-central Alaska is a major right lateral strike-slip fault that parallels the Alaska Range for much of its length. This fault represents the largest seismogenic source for interior Alaska but due to its remote location and difficulty of access, a dearth of paleoearthquake (PEQ) information exists for this important feature. The fault system is over 1200 km in length and identification of paleoseismic sites that preserve more that 2-3 PEQs has proven challenging. In 2012 and 2015, we developed the ‘Dead Mouse’ site, which provides the first long PEQ record west of the 2002 rupture extent. This site is located on the west-central segment of the DF near the southernmost intersection of the Parks Highway and the Nenana River (63.45285, -148.80249). We hand-excavated three fault-perpendicular trenches and documented new evidence for six surface rupturing PEQs from deformation in the upper 2.5 m of stratigraphy. Evidence for these events include offset stratigraphy, filled fissures, upward fault terminations, and an angular unconformity. Radiocarbon constraints on earthquake timing are based upon OxCal sequence modeling, which reveals the following 2-σ age distributions; E1 to 440- 316 cal yr BP, E2 to 835-740 cal yr BP, E3 to 1387-1126 cal yr BP, E4 to 3790-3020 cal yr BP, E5 to 5161-4531 cal yr BP and E6 to 7264-4943 cal yr BP.

Digital Object Identifier (DOI)

https://doi.org/10.13023/ETD.2016.433

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