Slope failures within and upstream of Lake Quinault, Washington, as uneven responses to Holocene earthquakes along the Cascadia subduction zone

Elana L. Leithold, Karl W. Wegmann, Delwayne R. Bohnenstiehl, Stephen G. Smith, Anders Noren, Ryan O'Grady

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Investigation of Lake Quinault in western Washington, including a reflection seismic survey, analysis of piston cores, and preliminary mapping in the steep, landslide-prone Quinault River catchment upstream of the lake, reveals evidence for three episodes of earthquake disturbance in the past 3000 yr. These earthquakes triggered failures on the lake's underwater slopes and delta front, as well as subaerial landsliding, partial channel blockage, and forced fluvial sediment aggradation. The ages of the three Lake Quinault disturbance events overlap with those of coseismically subsided, coastal marsh soils nearby in southwest Washington that are interpreted to record ruptures of the Cascadia megathrust. Absent from Lake Quinault, however, are signals of obvious disturbance from five additional subduction earthquakes inferred to have occurred during the period of record. The lack of evidence for these events may reflect the limitations of the data set derived from the detrital, river-dominated lake stratigraphy but may also have bearing on debates about segmentation and the distribution of slip along the Cascadia subduction zone during prior earthquakes.

Original languageEnglish (US)
Pages (from-to)178-200
Number of pages23
JournalQuaternary Research (United States)
Volume89
Issue number1
DOIs
StatePublished - Jan 1 2018

Keywords

  • Cascadia
  • Earthquake
  • Lakes
  • Paleoseismic
  • Sediment

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