Cascadia Subduction Zone Earthquakes by Cascadia Region Earthquake ...

For instance, the Huu-ay-aht legend of a large earthquake and ocean wave devastating their settlements at Pachena Bay places the event on a winter evening shortly after the village's residents had gone to sleep (consistent with the 9pm reconstructed time). Some of the stories contain temporal clues-such as a time estimate in generations since the event -which suggest a date range in the late 1600s or early 1700s, or which concur with the event's timing in other ways. These do not specify a date, and not all earthquake stories in the region can be ascribed to the 1700 quake however, virtually all of the native peoples in the region have at least one traditional story of an event of unmatched destructive power.

The contemporary indigenous groups of Cascadia had no known written documentation like that of the Japanese tsunami, but numerous oral traditions describing a great earthquake and inundation exist among indigenous coastal peoples from British Columbia to Northern California. Archaeological research in the region has uncovered evidence of several coastal villages having been flooded and abandoned around 1700. Core samples from the ocean floor, as well as debris samples from some earthquake-induced landslides in the Pacific Northwest, also support this timing of the event. Sediment layers in these locations demonstrate a pattern consistent with seismic and tsunami events around this time. This includes both inland stands of trees, such as one on the Copalis River in Washington, and pockets of tree stumps that are now under the ocean surface and become exposed only at low tide. The most important clue linking the tsunami in Japan and the earthquake in the Pacific Northwest comes from studies of tree rings ( dendrochronology), which show that several ' ghost forests' of red cedar trees in Oregon and Washington, killed by lowering of coastal forests into the tidal zone by the earthquake, have outermost growth rings that formed in 1699, the last growing season before the tsunami.

The Japanese records exist primarily in the modern-day Iwate Prefecture, in communities such as Tsugaruishi, Miyako (Kuwagasaki) and Ōtsuchi. Although there are no written records for the region from the time, the timing of the earthquake has been inferred from Japanese records of a tsunami that does not correlate with any other Pacific Rim quake. The earthquake took place at about 21:00 Pacific Time on Janu( NS).

Cascadia Subduction Zone Earthquakes by Cascadia Region Earthquake ...