The last known great earthquake in the northwest was the 1700 Cascadia... - dofaq.co
cascadia subduction zone

The last known great earthquake in the northwest was the 1700 Cascadia...

wikipedia - 16 Jul 2015
The last known great earthquake in the northwest was the 1700 Cascadia earthquake. Geological evidence indicates that great earthquakes (> magnitude 8.0) may have occurred sporadically at least seven times in the last 3,500 years, suggesting a return time of about 500 years. Seafloor core evidence indicates that there have been forty-one subduction zone earthquakes on the Cascadia subduction zone in the past 10,000 years, suggesting a general average earthquake recurrence interval of only 243 years. Of t

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