1700 Cascadia Earthquake

A megathrust earthquake of estimated moment magnitude 8.7 to 9.2 ruptured roughly 1,000 kilometers of the Cascadia subduction zone off the Pacific Northwest coast of North America on the night of 26 January 1700, with the Juan de Fuca plate slipping an average of 20 meters. No written record of the quake itself survives in North America, but its date was reconstructed from Japanese records of an unexplained tsunami that struck Honshu's coast the following day, from tree rings in Oregon and Washington ghost forests of cedars killed when the coastline suddenly subsided, and from Pacific Northwest indigenous oral traditions describing a catastrophic nighttime earthquake and flood.