Catalog Datasets Tsunami Historical Series: Cascadia - 1700 Details Permalink to Details Added to the Catalog 21 Jan. 2016 Available for SOS Explorer Categories People: History Water: Tsunamis Keywords Bathymetry Cascadia Earthquakes Model Oceans Seismic Waves Tectonics Tsunamis Waves Download Dataset Files (FTP) Video (Download) Image (Download) window.PLAYLIST_META = Object.assign({ url: "/catalog/datasets/tsunami-historical-series-cascadia-1700/" }, {"id":590,"name":"Tsunami Historical Series: Cascadia - 1700","thumbnailBig":"/ftp_mirror/oceans/tsunami_historical_series/cascadia/media/thumbnail_big.jpg","variations":[]}); Add to Playlist Added! View My Playlist Description Permalink to Description Just before midnight on January 27, 1700 a tsunami struck the coasts of Japan without warning since no one in Japan felt the earthquake that must have caused it. Nearly 300 years later scientists and historians in Japan and the United States solved the mystery of what caused this "orphan tsunami" through careful analysis of historical records in Japan as well as oral histories of Native Americans, sediment deposits, and ghost forests of drowned trees in the Pacific Northwest of North America, a region also known as Cascadia. They learned that this geologically active region, the Cascadia Subduction Zone, not only hosts erupting volcanoes but also produces megathrust earthquakes capable of generating devastating, ocean-crossing tsunamis. By comparing the tree rings of dead trees with those still living they could tell when the last of these great earthquakes struck the region. The trees all died in the winter of 1699 - 1700 when the coasts of northern California, Oregon, and Washington suddenly dropped 1- 2 m (3.3 - 6.6 ft.), flooding them with seawater. That much motion over such a large area requires a very large earthquake to explain it - perhaps as large as 9.2 magnitude, comparable to the Great Alaska Earthquake of 1964. Such an earthquake would have ruptured the earth along the entire length of the 1000 km (~600 mi) long fault of the Cascadia Subduction Zone and severe shaking could have lasted for 5 minutes or longer. Its tsunami would cross the Pacific Ocean and reach Japan in about 9 hours, so the earthquake must have occurred around 9:00 at night in Cascadia on January 26, 1700 (05:00 January 27 UTC).