Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5786641 | Quaternary Science Reviews | 2017 | 21 Pages |
Abstract
The relative magnitude of plate-boundary earthquakes at the northern end of the Cascadia subduction zone was assessed from the temporal concordance between the ages of coseismically buried late Holocene soils in southwest Washington, their counterparts in central and southern Cascadia, offshore turbidites, and paleoseismic deposits on the west coast of Vancouver Island. Only three of the seven buried soils in southwest Washington that can be reliably traced as buried soils or paleotsunami deposits in the coastal lowlands of south-central and southern Cascadia have well-dated counterparts in northern Cascadia. The three wide-ranging events date from Cascadia earthquakes Y (â¼250 cal BP), U (â¼1260 cal BP), and N (â¼2520 cal BP). All three likely ruptured the entire plate margin, and therefore potentially qualify as “giants” (Mw â¥Â 9). Deposits that may derive from tsunamis generated by earthquakes S (â¼1570 cal BP), L (â¼2870 cal BP) and J (â¼3360 cal BP) can also be found in northern Cascadia, but the ages of these deposits are not yet well-enough constrained to determine whether they are coeval with their southern counterparts. Earthquake W (â¼850 cal BP), appears to be present in the northern Cascadia paleoseismic record, but yields considerably older ages than in central Cascadia, and may be missing from southernmost Cascadia. The onshore record of an offshore turbidite (T2) displays a similar spatio-temporal pattern to that of earthquake W.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Ian Hutchinson, John Clague,