1700 Cascadia earthquake
 |
|
| Date | January 26, 1700 |
|---|---|
| Origin time | 21:00 local time |
| Magnitude | 8.7–9.2 Mw |
| Epicenter | 45°N 125°W / 45°N 125°WCoordinates: 45°N 125°W / 45°N 125°W |
| Fault | Cascadia subduction zone |
| Type | Megathrust |
| Tsunami | Yes |
The 1700 Cascadia earthquake occurred along the Cascadia subduction zone on January 26 with an estimated moment magnitude of 8.7–9.2. The megathrust earthquake involved the Juan de Fuca Plate that underlies the Pacific Ocean, from mid-Vancouver Island in British Columbia, Canada, south along the Pacific Northwest coast as far as northern California. The length of the fault rupture was about 1,000 kilometers (620 miles) with an average slip of 20 meters (66 ft).
The earthquake caused a tsunami that struck the coast of Japan, and may also be linked to the Bonneville Slide and the Tseax Cone eruption in British Columbia.
It is suggested that the 1700 earthquake took place at about 21:00 on January 26, 1700 (NS). Although there are no written records for the region from the time, the timing of earthquake has been inferred from Japanese records of a tsunami that does not correlate with any other Pacific Rim earthquake. The Japanese records exist primarily in the prefecture of Iwate, in communities such as Tsugaruishi, Kuwagasaki and Ōtsuchi.
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. 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.
...
Wikipedia