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Article
Late Holocene Tsunami Deposits at Salt Creek, Washington, USA
Science of Tsunami Hazards
  • Ian Hutchinson, Simon Fraser University
  • Curt D. Peterson, Portland State University
  • Sarah L. Sterling, Portland State University
Document Type
Article
Publication Date
10-1-2013
Subjects
  • Tsunamis -- Northwest,
  • Cascadia Subduction Zone,
  • Sediments (Geology) -- Northwest,
  • Strait of Juan de Fuca (B.C. and Wash.)
Abstract

We interpret two thin sand layers in the estuarine marsh at Salt Creek, on the southern shore of the Strait of Juan de Fuca, as the products of tsunamis propagated by earthquakes at the Cascadia subduction zone. The sand layers extend for about 60 m along the left bank of the creek about 800 m from the mouth, and can be traced to the base of a nearby upland area. One layer is exposed in the creek bank about 400 m further upstream, but they are only patchily distributed in the rest of the central area of the marsh. Both layers contain brackish-marine epipsammic diatoms. The lower sand layer marks a sharp contact between intertidal peaty mud and overlying mud, perhaps reflecting modest coseismic subsidence in association with tsunami deposition, but little or no change in the bracketing sediment occurs in association with the upper sand layer. The ages of the sand layers are not closely constrained, but were most likely deposited by tsunamis generated by great earthquakes at the Cascadia subduction zone about 1650 and 1300 years ago. The Cascadia great earthquake of AD1700 may have induced slight subsidence in the marsh, but no tsunami deposit was detected at the inferred contact. The absence of deposits from the marsh immediately inland of the 4 m-high barrier beach indicates that the largest tsunamis in the late Holocene at this site have not overtopped the barrier, which suggests that these tsunamis were likely only 2-3 m high.

Description

© 2014 Hutchinson, Peterson and Sterling. This article was original published in Science of Tsunami Hazards and can be found online at: http://tsunamisociety.org/

Permission to use research articles or photographs from the Journal should be requested directly from the authors

Persistent Identifier
http://archives.pdx.edu/ds/psu/12419
Citation Information
Ian Hutchinson, Curt D. Peterson and Sarah L. Sterling (2013). Late Holocene tsunami deposits at Salt Creek, Washington, USA. Science of Tsunami Hazards vol. 32, pp. 221-235.