The 1700 Cascadia earthquake occurred along the

Cascadia subduction zone The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, a ...

on January 26, 1700, with an estimated

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

of 8.7–9.2. The

megathrust earthquake Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthqu ...

involved the Juan de Fuca Plate from mid-

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest by ...

, south along the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Tho ...

coast as far as northern California. The length of the fault rupture was about , with an average slip of . The earthquake caused a

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

which struck the west coast of North America and the coast of Japan. Japanese tsunami records, along with reconstructions of the wave moving across the ocean, put the earthquake at about 9pm on the evening of 26 January 1700. Cascadia subduction zone USGS

Evidence

The earthquake took place at about 21:00

Pacific Time The Pacific Time Zone (PT) is a time zone encompassing parts of western Canada, the western United States, and western Mexico. Places in this zone observe standard time by subtracting eight hours from Coordinated Universal Time ( UTC−08:00). ...

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.

Scientific research

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 Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

and

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

, 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."Jan. 26, 1700: How Scientists Know When The Last Big Earthquake Happened Here"

Oregon Public Broadcasting Oregon Public Broadcasting (OPB) is the primary television and radio public broadcasting network for most of the U.S. state of Oregon as well as southern Washington. OPB consists of five full-power television stations, dozens of VHF or UHF tra ...

, January 26, 2015. Sediment layers in these locations demonstrate a pattern consistent with seismic and tsunami events around this time. 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. Archaeological research in the region has uncovered evidence of several coastal villages having been flooded and abandoned around 1700.

Cultural research

The contemporary indigenous groups of Cascadia had no known written documentation like that of the Japanese tsunami, but numerous

oral tradition Oral tradition, or oral lore, is a form of human communication wherein knowledge, art, ideas and cultural material is received, preserved, and transmitted orally from one generation to another. Vansina, Jan: ''Oral Tradition as History'' (1985) ...

s describing a great earthquake and inundation exist among indigenous coastal peoples from British Columbia to Northern California. 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. Some of the stories contain temporal clues — such as a time estimate in

generation A generation refers to all of the people born and living at about the same time, regarded collectively. It can also be described as, "the average period, generally considered to be about 20–⁠30 years, during which children are born and gr ...

s 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. 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). Every community on Pachena Bay was wiped out except for Masit on a mountainside above sea level. The only other survivor was Anacla aq sop, a young woman who happened to be staying that day at Kiix-in on the more tsunami-sheltered

Barkley Sound , image = Fishing boat in the Broken Group Islands.jpg , image_size = 260px , alt = , caption = Barkley Sound , image_bathymetry = , alt_bathymetry = , caption_bathymetry = , locat ...

. Kwakwaka'wakw (Kwakiutl) stories from the north end of Vancouver Island report a night-time earthquake that caused virtually all houses in their community to collapse; Cowichan stories from Vancouver Island's inner coast speak of a nighttime earthquake, causing a landslide that buried an entire village.

Makah The Makah (; Klallam: ''màq̓áʔa'')Renker, Ann M., and Gunther, Erna (1990). "Makah". In "Northwest Coast", ed. Wayne Suttles. Vol. 7 of '' Handbook of North American Indians'', ed. William C. Sturtevant. Washington, D.C.: Smithsonian Instit ...

stories from Washington speak of a great night-time earthquake, of which the only survivors were those who fled inland before the tsunami hit. The

Quileute The Quileute , are a Native American people in western Washington state in the United States, currently numbering approximately 2,000. They are a federally recognized tribe: the ''Quileute Tribe of the Quileute Reservation''. The Quileute peo ...

people in Washington have a story about a flood so powerful that villagers in their canoes were swept inland all the way to

Hood Canal Hood Canal is a fjord forming the western lobe, and one of the four main basins,"Haida Gwaii Quake Brings Home the Importance of Quileute Relocation Legislation"
. ''

Indian Country Today Media Network ''ICT News'' (formerly known as ''Indian Country Today'') is a daily digital news platform that covers the Indigenous world, including American Indians, Alaska Natives and First Nations. It was founded in 1981 as a weekly print newspaper, ''The ...

'', November 6, 2012.

Ethnographic Ethnography (from Greek ''ethnos'' "folk, people, nation" and ''grapho'' "I write") is a branch of anthropology and the systematic study of individual cultures. Ethnography explores cultural phenomena from the point of view of the subject ...

research has focused on a common regional pattern of art and

mythology Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. Since "myth" is widely used to imply that a story is not objectively true, the identification of a narra ...

depicting a great battle between a

thunderbird Thunderbird, thunder bird or thunderbirds may refer to: * Thunderbird (mythology), a legendary creature in certain North American indigenous peoples' history and culture * Ford Thunderbird, a car Birds * Dromornithidae, extinct flightless birds ...

and a

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

, as well as cultural signifiers such as earthquake-inspired ritual masks and dances.

Future threats

The geological record reveals that "great earthquakes" (those with

8 or higher) occur in the

about every 500 years on average, often accompanied by

s. There is evidence of at least 13 events at intervals from about 300 to 900 years with an average of 570–590 years. Previous earthquakes are estimated to have been in AD 1310, AD 810, AD 400, 170 BC and 600 BC. Cascadia earthquake sources

As seen in the 1700 quake, the 2004 Indian Ocean earthquake, and the

2011 Tōhoku earthquake and tsunami The occurred at 14:46 JST (05:46 UTC) on 11 March. The magnitude 9.0–9.1 (M) undersea megathrust earthquake had an epicenter in the Pacific Ocean, east of the Oshika Peninsula of the Tōhoku region, and lasted approximately six mi ...

, subduction zone earthquakes can cause large tsunamis, and many coastal areas in the region have prepared tsunami evacuation plans in anticipation of a possible future Cascadia earthquake. However, the major nearby cities, notably

Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...

, Portland,

Vancouver Vancouver ( ) is a major city in western Canada, located in the Lower Mainland region of British Columbia. As the List of cities in British Columbia, most populous city in the province, the 2021 Canadian census recorded 662,248 people in the ...

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

, and Tacoma, which are located on inland waterways rather than on the coast, would be sheltered from the full brunt of a tsunami. These cities do have many vulnerable structures, especially bridges and unreinforced brick buildings; consequently, most of the damage to the cities would probably be from the earthquake itself. One expert asserts that buildings in Seattle are vastly inadequate even to withstand an event of the size of the 1906 San Francisco earthquake, let alone any more powerful one. Kenneth Murphy, who directs

FEMA The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Ex ...

's Region X, the division responsible for Oregon, Washington, Idaho, and Alaska, put it quite dramatically: "Our operating assumption is that everything west of

Interstate 5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...

will be toast." Recent findings conclude that the Cascadia subduction zone is more complex and volatile than previously believed. In 2010, geologists predicted a 37% chance of an M8.2+ event within 50 years, and a 10 to 15% chance that the entire Cascadia subduction zone will rupture with an M9+ event within the same time frame. Geologists have also determined the Pacific Northwest is not prepared for such a colossal quake. The tsunami produced could reach heights of . A 2004 study revealed the potential for relative mean

sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cry ...

(caused by subsidence) along the Cascadia subduction zone. It postulated that cities on the west coast of Vancouver Island, such as

Tofino Tofino ( ) is a town of approximately 2,516 residents on the west coast of Vancouver Island in the Canadian province of British Columbia. The District of Tofino is located at the western terminus of Highway 4 on the tip of the Esowista Peninsu ...

and

Ucluelet Ucluelet (, also Ukee) is a district municipality (population 1,717) on the Ucluelet Peninsula on the west coast of Vancouver Island in British Columbia, Canada. Ucluelet means "people of the safe harbour" in the indigenous Nuu-chah-nulth (No ...

, are at risk for a 1–2 m subsidence, relative to mean sea level. The confirmation of their oral traditions about a great earthquake has led many aboriginal groups in the area to initiate projects to relocate their coastal communities to higher and safer ground in preparation for the predicted next earthquake. The Huu-ay-aht People have rebuilt their administration building on a high point of land in their territory; coastal residents are immediately evacuated to this building whenever a tsunami warning is issued, as an interim measure toward eventually relocating all residents to higher ground. The

people secured a land grant from the federal government of the United States in 2012 to move their settlement inland, both as protection from a future tsunami threat and because of more frequent flooding on the Quillayute River. The Shoalwater Bay Indian Tribe has also set a goal of moving their community uphill and has received a FEMA PDM grant to build the first vertical evacuation tower on their coast, scheduled to be completed near the Tokeland Marina by 2022. Some other subduction zones have such earthquakes every 100 to 200 years; the longer interval results from slower plate motions. The rate of convergence between the Juan de Fuca Plate and the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacif ...

is per year.

Bridge of the Gods – Bonneville Slide

It was once conjectured that the Cascadia earthquake may also have been linked to the Bridge of the Gods – Bonneville Slide and the

Tseax Cone The Tseax Cone ( ), also called the Tseax River Cone or the Aiyansh Volcano, is a young and active cinder cone and adjacent lava flows associated with the Nass Ranges and the Northern Cordilleran Volcanic Province. It is located east of Crater ...

eruption in British Columbia, Canada. However, recent investigations using radiocarbon dating and dendrochronology date the Bonneville landslide around 1450.

References

External links

General

Cascadia Subduction Zone Earthquakes: A magnitude 9.0 earthquake scenario
– The Cascadia Region Earthquake Workgroup 2005
Tsunami Animation: Cascadia 1700
–

Pacific Tsunami Warning Center The Pacific Tsunami Warning Center (PTWC) is one of two tsunami warning centers that are operated by NOAA in the United States. Headquartered on Ford Island, HI, the PTWC is part of an international tsunami warning system (TWS) program and s ...

USGS Scientist Shows Evidence for 300-Year-Old Tsunami to Participants in International Tsunami Training Institute
– USGS

Native and Japanese accounts

Native American Stories expand history
– Pacific Northwest Seismic Network
Native American Legends of Tsunamis in Pacific NW
–

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

Fault slip and seismic moment of the 1700 Cascadia earthquake inferred from Japanese tsunami descriptions
–

Journal of Geophysical Research The ''Journal of Geophysical Research'' is a peer-reviewed scientific journal. It is the flagship journal of the American Geophysical Union. It contains original research on the physical, chemical, and biological processes that contribute to the un ...

Japanese Shipwreck Adds To Evidence Of Great Cascadia Earthquake In 1700
– '' ScienceDaily'' *

Current hazards

Surviving a Tsunami—Lessons from Chile, Hawaii, and Japan
–

Big earthquake coming sooner than we thought, Oregon geologist says
– ''

The Oregonian ''The Oregonian'' is a daily newspaper based in Portland, Oregon, United States, owned by Advance Publications. It is the oldest continuously published newspaper on the U.S. west coast, founded as a weekly by Thomas J. Dryer on December 4, 18 ...

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