Cascadia Subduction Zone: A Summary
Cascadia Subduction Zone: A Summary of History
Marcellina MacArthur
Washington State University
Abstract
Research shows that there is a pattern of quakes that range from 8.7 to 9.2 that occur every 240 years or so, and we know this because Oregon State University has done a 13 year study on the margin stretching from southern Vancouver Island to the Oregon-California border. The last mega-earthquake in the Pacific-Northwest being on January 26, 1700; We know this because written records in Japan document how a tsunami destroyed that year’s rice crop stored in warehouses. We also know from documentation of data that scientists have collected from when there are off shore earthquakes, these quakes will cause mud and sand to “slide” down the continental margins into undersea canyons. These coarse sediments called turbides stand out from the fine particulate that accumulates normally. By dating these particles (using Carbon-14 analysis) researchers can estimate with some degree of accuracy that …show more content…
Major canyon/channel systems are outlined in blue. Bathymetric grid constructed from newly collected multibeam data in 1999, Gorda Plate swath bathymetry collected in 1997 (Dziak et al., 2001), and archive data available from NGDC. Primary core sites shown with yellow rim, all other 19992002 cores are grey. White core numbers preceded with cruise number “M9907”, collected on the RV Melville, Yellow symbols are preceded with the cruise designation “RR0207”, collected on the R/V Revelle. Core EW950416PC shown in red. Earlier OSU cores are shown in grey. “PC” = Piston Core; “BC” = Box Core; “KC = Kasten core; “GC” = Gravity core; “TC” = Trigger core. Trigger cores omitted for clarity. Inset of Effingham Inlet shows collection site of Pacific Geoscience Centre (PGC) collected piston cores (http://activetectonics.coas.oregonstate.edu/Cascadia_turbs.htm)
Marcellina MacArthur
Washington State University
Abstract
Research shows that there is a pattern of quakes that range from 8.7 to 9.2 that occur every 240 years or so, and we know this because Oregon State University has done a 13 year study on the margin stretching from southern Vancouver Island to the Oregon-California border. The last mega-earthquake in the Pacific-Northwest being on January 26, 1700; We know this because written records in Japan document how a tsunami destroyed that year’s rice crop stored in warehouses. We also know from documentation of data that scientists have collected from when there are off shore earthquakes, these quakes will cause mud and sand to “slide” down the continental margins into undersea canyons. These coarse sediments called turbides stand out from the fine particulate that accumulates normally. By dating these particles (using Carbon-14 analysis) researchers can estimate with some degree of accuracy that …show more content…
Major canyon/channel systems are outlined in blue. Bathymetric grid constructed from newly collected multibeam data in 1999, Gorda Plate swath bathymetry collected in 1997 (Dziak et al., 2001), and archive data available from NGDC. Primary core sites shown with yellow rim, all other 19992002 cores are grey. White core numbers preceded with cruise number “M9907”, collected on the RV Melville, Yellow symbols are preceded with the cruise designation “RR0207”, collected on the R/V Revelle. Core EW950416PC shown in red. Earlier OSU cores are shown in grey. “PC” = Piston Core; “BC” = Box Core; “KC = Kasten core; “GC” = Gravity core; “TC” = Trigger core. Trigger cores omitted for clarity. Inset of Effingham Inlet shows collection site of Pacific Geoscience Centre (PGC) collected piston cores (http://activetectonics.coas.oregonstate.edu/Cascadia_turbs.htm)