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, and ...

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

, 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. Though ...

coast as far as

northern California Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers incl ...

. 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 explo ...

which struck the west coast of North America and the coast of

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. 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 The Pacific Rim comprises the lands around the rim of the Pacific Ocean. The ''Pacific Basin'' includes the Pacific Rim and the islands in the Pacific Ocean. The Pacific Rim roughly overlaps with the geologic Pacific Ring of Fire. List of co ...

quake. The Japanese records exist primarily in the modern-day

Iwate Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. It is the second-largest Japanese prefecture at , with a population of 1,210,534 (as of October 1, 2020). Iwate Prefecture borders Aomori Prefecture to the north, Akita Prefectur ...

, in communities such as Tsugaruishi, Miyako (Kuwagasaki) and

Ōtsuchi An is a large wooden war mallet used by the samurai class of feudal Japan. The ōtsuchi had a shaft of about much like the ono (war axe). It was mainly used for door breaching Door breaching is a process used by military, police, or emerg ...

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 Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atmos ...

), which show that several "

ghost forest Ghost forests are areas of dead trees in former forests, typically in coastal regions where rising sea levels or tectonic shifts have altered the height of a land mass. Forests located near the coast or estuaries may also be at risk of dying thro ...

s" of red cedar trees in

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

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 on ...

, 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, 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

landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...

s 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 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. For instance, the Huu-ay-aht legend of a large earthquake and ocean wave devastating their settlements at

Pachena Bay Pachena Bay is located south of Bamfield in Pacific Rim National Park at the southern end of Vancouver Island, British Columbia, Canada. It was the location of a First Nation's village that was destroyed by a tsunami in 1700. Origin of name ...

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. 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

that buried an entire village. Makah 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 peop ...

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."Haida Gwaii Quake Brings Home the Importance of Quileute Relocation Legislation"
. '' Indian Country Today Media Network'', November 6, 2012. Ethnographic 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 narrat ...

depicting a great battle between a thunderbird 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 moment magnitude 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 An earthquake and a tsunami, known as the Boxing Day Tsunami and, by the scientific community, the Sumatra–Andaman earthquake, occurred at 07:58:53 local time (UTC+7) on 26 December 2004, with an epicentre off the west coast of northern Suma ...

, 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 minutes ...

, 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 Portland most commonly refers to: * Portland, Oregon, the largest city in the state of Oregon, in the Pacific Northwest region of the United States * Portland, Maine, the largest city in the state of Maine, in the New England region of the northeas ...

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, 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 At 05:12 Pacific Standard Time on Wednesday, April 18, 1906, the coast of Northern California was struck by a major earthquake with an estimated moment magnitude of 7.9 and a maximum Mercalli intensity of XI (''Extreme''). High-intensity sha ...

, 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 Exec ...

'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 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 and Ucluelet, 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 Quillayute River (also spelled Quileute River) is a river situated on the Olympic Peninsula in Washington. It empties to the Pacific Ocean at La Push, Washington. The Quillayute River is formed by the confluence of the Bogachiel River, Cal ...

. 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 Pacific ...

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 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
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 The Pacific Northwest Seismic Network, or PNSN, collects and studies ground motions from about 400 seismometers in the U.S. states of Oregon and Washington. PNSN monitors volcanic and tectonic activity, gives advice and information to the public ...

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 ''Science Daily'' is an American website launched in 1995 that aggregates press releases and publishes lightly edited press releases (a practice called churnalism) about science, similar to Phys.org and EurekAlert!. The site was founded by mar ...

'' *

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, 185 ...

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