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1700 Cascadia earthquake

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Coordinates: 45°N 125°W / 45°N 125°W / 45; -125

From Wikipedia, the free encyclopedia

Megathrust earthquake in the Pacific Northwest region

"},"duration":{"wt":""},"magnitude":{"wt":"8.7–9.2 {{M|w|link=y}}{{harvnb|Atwater|Musumi-Rokkaku|Satake|Yoshinobu|2005|p=98}}"},"depth":{"wt":""},"coordinates":{"wt":"{{coord|45|-125|type:event|display=inline,title}}"},"fault":{"wt":"[[Cascadia subduction zone]]"},"type":{"wt":"[[Megathrust earthquake|Megathrust]]"},"areas_affected":{"wt":""},"damage":{"wt":""},"max_intensity":{"wt":""},"pga":{"wt":""},"tsunami":{"wt":"Yes"},"landslide":{"wt":""},"foreshocks":{"wt":""},"aftershocks":{"wt":""},"casualties":{"wt":"Many Native Americans killed or displaced by shaking or subsequent tsunami"},"anss_url":{"wt":"official17000127050000000"}},"i":0}}]}'>1700 Cascadia earthquake

Location within North America

USGS-ANSSComCat

Local dateJanuary 26, 1700; 326 years ago (1700-01-26)

Local timecirca 21:00 PST[1]

Magnitude8.7–9.2 Moment mag. scale"}]]}'>Mw[2]

Epicenter45°N 125°W / 45°N 125°W / 45; -125[[Geographic coordinate system|Coordinates]]: {{#parsoid\u0000fragment:13}}[https://geohack.toolforge.org/geohack.php?pagename=1700_Cascadia_earthquake&params=45_N_125_W_type:event 45°N 125°W&#xfeff; / &#xfeff;45°N 125°W&#xfeff; / 45; -125][[Category:Pages using gadget WikiMiniAtlas]]"}}'/>[1]FaultCascadia subduction zoneTypeMegathrustTsunamiYesCasualtiesMany Native Americans killed or displaced by shaking or subsequent tsunami<br>The 1700 Cascadia earthquake occurred along the Cascadia subduction zone on January 26, 1700, with an estimated moment magnitude of 8.7–9.2. The megathrust earthquake involved the Juan de Fuca plate from mid-Vancouver Island, south along the Pacific Northwest coast as far as northern California. The plate slipped an average of 20 meters (66 feet) along a fault rupture about 1,000 kilometers (600 miles) long.

The earthquake caused a tsunami which struck the west coast of North America and the coast of Japan.[3] Japanese tsunami records, along with reconstructions of the wave moving across the ocean, put the earthquake at about 9:00 PM Pacific Time on the evening of 26 January 1700.[4]

Cascadia subduction zone<br>Sandsheet thought to have resulted from the tsunami caused by the 1700 earthquake, exposed on the bank of the Salmon River, Oregon

Japanese records<br>[edit]

The earthquake took place at about 21:00 PT on January 26, 1700 (NS). 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 Japanese records exist primarily in the modern-day Iwate Prefecture, in communities such as Tsugaruishi, Miyako (Kuwagasaki) and Ōtsuchi. The fact that the waves were recorded as striking Ōtsuchi and Kuwagasaki on the same day and hour helped researchers pinpoint the estimated date, time, and place of origin of the earthquake.[4][5]

According to Japanese records, destructive waves hit towns along the Pacific Coast of Japan on the 8th and 9th days of the 12th month of Genroku 12, which would be equivalent to January 27 and 28, 1700. Based on the damage reports in Japanese records, the maximum wave heights were estimated to be in the range of 2–5 meters. At Kuwagasaki, 13 houses were destroyed by flooding and 20 in a subsequent fire, representing about 10% of all buildings in the town. At Ōtsuchi, two buildings and two salt kilns were damaged and some fields and paddies were also flooded. At Miho, the village headman observed the waves and warned the villagers to flee to higher ground. No damage was reported there. At Nakaminato, where oceangoing ships unloaded their cargoes to smaller vessels to travel by river to Edo (now Tokyo), a ship carrying 28 metric tons of rice was unable to enter the port due to high waves. Later that evening, a storm drove it onto a rocky shore, killing two sailors and destroying the cargo. In the Tanabe area, the waves flooded wheat fields, rice paddies, and a storehouse, and ascended the moat of Tanabe Castle [ja].[5]

As no one in Japan had felt an earthquake before the waves struck, many writers were reluctant to call them a tsunami, with some referring to them as merely high tide or high waves. An observer at Kuwagasaki called it a tsunami while the village headman of Miho was puzzled after observing that the waves behaved like a tsunami but no earthquake had been felt in the area.[5]

Scientific research<br>[edit]

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...