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Paleoseismology of the Denali fault system at the Schist Creek site, central Alaska

Open-File Report 2015-1225
Prepared in cooperation with the Alaska Division of Geological and Geophysical Surveys and the University of Alaska–Fairbanks
By: , , , and 
https://doi.org/10.3133/ofr20151225

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Abstract

Two hand-dug trenches at the Schist Creek site on the Denali fault system in central Alaska exposed evidence of four surface-rupturing earthquakes on the basis of upward terminations of fault strands and at least one buried, scarp-derived colluvial wedge. Limited radiocarbon ages provide some constraints on times of the ruptures. The youngest rupture (PE1) likely occurred about 200–400 years ago, the penultimate rupture (PE2) is younger than 1,200 years old, the third event back (PE3) occurred between 1,200 and 2,700 years ago, and the oldest rupture (PE4) occurred more than 2,700 and less than 17,000 years ago. Evidence for a possible additional rupture (PE4?) is equivocal and probably is related to earthquake PE4. On the basis of a nearby measured slip rate of 9.4 ± 1.6 millimeters per year and the long interevent times between our documented ruptures, we believe that our paleoseismic record at this site is incomplete. We suspect one undocumented earthquake between PE1 and PE2 and one or perhaps two more earthquakes between PE2 and PE3. We found stratigraphic evidence in the trenches for only four or possibly five (PE4?) earthquakes, but the addition of two or three inferred earthquakes yields a record of eight possible surface ruptures at the Schist Creek site. Our interpretation of the paleoseismic history at the site is consistent with recurrence intervals of several hundred years on this section of the Denali fault system.

Suggested Citation

Personius, S.F., Crone, A.J., Burns, P.A.C, and Rozell, Ned, 2015, Paleoseismology of the Denali fault system at the Schist Creek site, central Alaska: U.S. Geological Survey Open-File Report 2015-1225, 15 p., 1 oversize plate, http://dx.doi.org/10.3133/ofr20151225.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • The 2002 Denali Fault Earthquake
  • Schist Creek Trench Site
  • Discussion
  • Conclusions
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Paleoseismology of the Denali fault system at the Schist Creek site, central Alaska
Series title Open-File Report
Series number 2015-1225
DOI 10.3133/ofr20151225
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Geologic Hazards Science Center
Description iii, 15 p.
Country United States
State Alaska
Other Geospatial Schist Creek
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details