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I-MAG STS    Corporation
The Cascadian subduction zone stretches from north of Vancouver Island to
northern California. The Cascadian fault separates the Juan de Fuca and North
America plates. It is not inaccurate to describe the Juan de Fuca, already the
smallest of Earth's tectonic plates, as three platelets: the Explorer Plate (northern
near the west coast of Vancouver Island); the Juan de Fuca Plate (central offshore
of Washington and Oregon) and the Gorda Plate (south; offshore near the
northern border of California). The last known great earthquake in the northwest
was the Cascadia Earthquake in January 1700. Although there is some dispute
about approximate dates [Brian Atwater; Martitia Tuttle, Eugene Schweig, Charles
Rubin, David Yamaguchi, Eileen Hemphill-Haley (2003). "Earthquake Recurrence
Inferred from Paleoseismology". Developments in Quaternary Science (Elsevier
BV) 1: 331–350 and Brian Atwater; Musumi-Rokkaku Satoko, Satake Kenji, Tsuji
Yoshinobu, Ueda Kazue, David Yamaguchi (2005) The Orphan Tsunami of 1700 —
Japanese Clues to a Parent Earthquake in North America (U.S. Geological Survey
Professional Paper 1707]  geological evidence indicates that there have been at
least six other major earthquakes in the last 3,500 years. Based on the small
sample size, we are reluctant to say that southern Cascadian seismic events trigger
northern San Andreas events. Even without that connection, a major Cascadian
event with tsunamis would be disastrous.
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