Detection of Large Prehistoric Earthquakes in the Pacific Northwest by Microfossil Analysis

Geologic and palynological evidence for rapid sea level change ∼3400 and ∼2000 carbon-14 years ago (3600 and 1900 calendar years ago) has been found at sites up to 110 kilometers apart in southwestern British Columbia. Submergence on southern Vancouver Island and slight emergence on the mainland dur...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1994-04, Vol.264 (5159), p.688-691
Main Authors: Mathewes, Rolf W., Clague, John J.
Format: Article
Language:English
Subjects:
British Columbia
Diatoms
Earth sciences
Earth, ocean, space
Earthquakes
Earthquakes, seismology
Exact sciences and technology
Fens
Holocene
Holocene Epoch
Internal geophysics
Marine
Marine and continental quaternary
Microfossils
Mud
Paleobotany
Paleontology
Peat
Pollen
Radiocarbon
Serpentine
Subsidence
Surficial geology
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Summary:Geologic and palynological evidence for rapid sea level change ∼3400 and ∼2000 carbon-14 years ago (3600 and 1900 calendar years ago) has been found at sites up to 110 kilometers apart in southwestern British Columbia. Submergence on southern Vancouver Island and slight emergence on the mainland during the older event are consistent with a great (magnitude M ≥ 8) earthquake on the Cascadia subduction zone. The younger event is characterized by submergence throughout the region and may also record a plate-boundary earthquake or a very large crustal or intraplate earthquake. Microfossil analysis can detect small amounts of coseismic uplift and subsidence that leave little or no lithostratigraphic signature.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.264.5159.688