The Epic B.C. Earthquake of 1700 AD

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An orphan forest created by the 1700 earthquake
It is the most powerful earthquake to occur in Canada in the past 1,000 years, and it would have an impact not only in Canada and the United States, but across the ocean as well.
On Jan. 26, 1700 at about 9 p.m., a 1,000-kilometre section of the Juan de Fuca Plate experienced a megathurst earthquake that pushed the plate 20 metres, resulting in an earthquake that measured an estimated 8.7 to 9.2 on the Richter Scale. The earthquake was so strong it released the same amount of energy as the United States consumes in an entire month today. It was also significantly stronger than the earthquake that hit San Francisco in 1906.
According to evidence based on Japanese records, it is believed that the earthquake took place at 7 p.m., sending a massive tsunami across the ocean towards Japan. The 1,000-kilometre section of land that moved ran from Vancouver Island all the way down to northern California.
Looking back at that date, apart from the written records by the Japanese concerning the tsunami, there are only oral stories told by the First Nations of the region impacted by the earthquake. It is hard to pinpoint if they are speaking of the 1700 earthquake, but there are stories of a major event that was very destructive around this time. Based on the number of generations going back to tell the stories of this event, it has been pinpointed to between the late-1600s and early-1700s. One legend speaks of a large earthquake and ocean wave that destroyed settlements at Pachina Bay. The only community on that bay not to be wiped out was Masit, due to the fact it was 75 feet above sea level. One First Nations woman was told to be the only survivor from Pachina Bay, simply because she was away at Barkley Sound when it happened.
On the north end of Vancouver Island, the First Nations people have a story of a night-time earthquake that destroyed nearly every house in the community. Another settlement was destroyed by a landslide at the same time, according to First Nations oral tales.
There is a great deal of physical evidence of an earthquake happening as well. There are several ghost forests of red cedars on the coast of Oregon and Washington, which were killed by the lowering of the coastal forest into a tidal zone by the earthquake. The outermost rings on these trees dates to 1699. Core samples done of the ocean floor also show debris from landslides in the Pacific Northwest and Lower Mainland around this time. The rings were also quite wide leading up to the last ring, which showed there was a sudden event that happened rather than a slow rise of the ocean.
In the 1980s and 1990s, scientists found that lands along the coast dropped suddenly and were covered in waves and mud. Delicate marsh plants that were alive were killed by the rapidly advancing seawater.
On the Japanese side of things, it is strongly believed that a large tsunami hit Japan about 10 hours following the earthquake. Japanese records describe waves that were six to 10 feet high, hitting the coast. Based on current research, it is believed the tsunami went two kilomtres up a river and destroyed farmed fields, fishermen’s shacks, a government warehouse and salt kilns.
Reports of the tsunami are found in official reports sent to Edo and in private family sources and histories. None of these reports speak of an earthquake in Japan, which lends evidence to linking the tsunami to the earthquake in British Columbia. For some time, the tsunami was called Japan’s “orphan” tsunami because there was no local earthquake to trigger it.
The Bridge of the Gods, which is a natural dam that was created by the Bonneville Slide, is believed by some researchers to have been caused by the 1700 earthquake. Recent work using radiocarbon dating has found that the slide links to an event that occurred between 1670 and 1760, which would put it in place for the earthquake.
A lava flow eruption also occurred on the Tseax Cone, which is located near Terrance B.C., around the time of the earthquake. The lava flow eruption is cited to have occurred between 1668 and 1714, damming the nearby river and forming a lava lake.
As for that fault, scientists had believed that it was dormant up until 20 years ago when it was determined that it has magnitude 8 or greater earthquakes every 500 years or so. It is believed that 13 earthquakes of this size have occurred over the course of 6,000 years.
Will the area see another large earthquake? Well, in Canadian History Ehx we deal with the past not the future but it is believed that a magnitude 9 quake happens every 526 years on average with 19 happening over the past 10,000 years. As for quakes that register 8 or higher, they happen every 234 years, which means the area is due.

Information for this piece came from Earthquakes Canada, Wikipedia,

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