Aquatic species, from barnacles to sea otters, thrive in the pockets of habitat created by the coastline’s sinuous edges. Tall, dense forests of pine, spruce, and cedar blanket the bioregion. The tail extends north to the southern tip of Alaska, and the whale’s open mouth, facing south, just catches northern California. Mountainous Vancouver Island is the pectoral fin. British Columbia’s temperate rainforest forms the bulk of its body, along with Washington state, Idaho, and much of Oregon. For their most recent publications and news, visit their website.If you look at a world map, Cascadia is shaped like a whale swimming south. The M9 Project, a University of Washington-based research group, has been producing research on Cascadia Subduction Zone hazards and effects of large earthquakes in the Paciifc Northwest since 2015.
WILL EUEGENE BE HIT BY CASCADEA FAULT LINE ON WEST COAST FULL
The geological evidence has led to different interpretations, moreover, about whether the entire CSZ always ruptures in great M9 earthquakes, or whether smaller M8 or M8.5-sized events also can break parts of the zone in between the full rupture events. Coupled with evident occurrence of great megathrust earthquakes, the CSZ must be much more strongly locked than other subduction faults. The CSZ may be unique among the world's subduction zones in that it produces very few (if any) earthquakes unambiguously on the plate interface. For more about the Cascadia Subduction Zone, visit the USGS webpage discussing this topic. To learn more about the history of the Cascadia Subduction Zone and the science that led to the discovery of it, delve into land level changes and turbidites created by the CSZ earthquakes. Geological evidence indicates that such great earthquakes have occurred at least seven times in the last 3,500 years, a return interval of 400 to 600 years. The last known megathrust earthquake in the northwest was in January, 1700, just over 300 years ago. The CSZ has produced magnitude 9.0 or greater earthquakes in the past, and undoubtedly will in the future. Great Subduction Zone earthquakes are the largest earthquakes in the world, and are the only source zones that can produce earthquakes greater than M8.5. From its surface trace offshore to a depth of possibly 5 km, all remote from land, observations are few and it remains unknown whether the fault is stuck or slipping silently. Below the transition zone geodetic evidence suggests that the fault slides continuously and silently at long term plate slip rate. This relieves the plate boundary stresses there, but adds to the stress on the locked part of the fault. The fault's frictional properties change with depth, such that immediately below the locked part is a strip (the "Transition Zone") that slides in " slow slip events" that slip a few cm every dozen months or so. The Juan de Fuca plate moves toward, and eventually is shoved beneath, the continent (North American plate).Īt depths shallower than 30 km or so, the CSZ is locked by friction while strain slowly builds up as the subduction forces act, until the fault's frictional strength is exceeded and the rocks slip past each other along the fault in a "megathrust" earthquake. New Juan de Fuca plate is created offshore along the Juan de Fuca ridge. It separates the Juan de Fuca and North America plates. The Cascadia Subduction Zone (CSZ) "megathrust" fault is a 1,000 km long dipping fault that stretches from Northern Vancouver Island to Cape Mendocino California.
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