1700 Cascadia earthquake
USGS-ANSS | ComCat |
---|---|
Local date | January 26, 1700 |
Local time | 21:00[1] |
Magnitude | 8.7–9.2 Mw[2] |
Epicenter | 45°N 125°W / 45°N 125°W[1] |
Fault | Cascadia subduction zone |
Type | Megathrust |
Tsunami | Yes |
Casualties | Many Native Americans killed or displaced by shaking or subsequent tsunami |
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 ft) along a fault rupture about 1,000 kilometers (620 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]
Evidence
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.[4]
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 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.[5] This includes both inland stands of trees, such as one on the Copalis River in Washington,[5] and pockets of tree stumps that are now under the ocean surface and become exposed only at low tide.[6]
Sediment layers in these locations demonstrate a pattern consistent with seismic and tsunami events around this time.[7] 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.[6] Archaeological research in the region has uncovered evidence of several coastal villages having been flooded and abandoned around 1700.[8]
Cultural research
The contemporary
Some of the stories contain temporal clues—such as a time estimate in generations since the event[8]—which suggest a date range in the late 1600s or early 1700s,[5] 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).[10] Every community on Pachena Bay was wiped out except for Masit on a mountainside 75 feet (23 m) above sea level.[11] The only other Panchena Bay survivor was a young woman named Anacla aq sop, who happened to be staying that day at Kiix-in, located on the less-tsunami-impacted Barkley Sound.
Future threats
The geological record reveals that great earthquakes with moment magnitude 8 or higher occur in the Cascadia subduction zone about every 500 years on average, often accompanied by tsunamis. There is evidence of at least 13 events at intervals from about 300 to 900 years with an average of 570–590 years.[15]
As seen in the 1700 quake, the
Kenneth Murphy, who directs FEMA's Region X, the division responsible for Oregon, Washington, Idaho, and Alaska, stated, "Our operating assumption is that everything west of Interstate 5 will be toast."[17]
Recent findings conclude that the Cascadia subduction zone is more complex and volatile than previously believed.[18] In 2010, geologists predicted a 37% chance of a magnitude 8.2+ event within 50 years, and a 10% to 15% chance that the entire Cascadia subduction zone will rupture with a magnitude 9+ event within the same time frame.[19][20] Geologists have also determined the Pacific Northwest is not prepared for such an earthquake. The tsunami produced could reach heights of 80 to 100 feet (24 to 30 m).[21]
A 2004 study revealed the potential for relative mean sea level rise (caused by subsidence of coastal land) 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-to-2-metre (3 ft 3 in to 6 ft 7 in) subsidence, relative to mean sea level.[22]
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.[10] The Huu-ay-aht People have rebuilt their administration building on a high point in their territory;[10] 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.[23] The Quileute people secured a land grant from the US government 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.[13] The Shoalwater Bay Indian Tribe also sought federal funding to move their community uphill receiving a FEMA PDM grant to build the first vertical evacuation tower on their coast, completed near the Tokeland Marina in 2022.[24][25]
In 2023, Washington scientists reported on a detailed study of a high-pressure and high-temperature seafloor seep, likely on the plate boundary, offshore of Oregon.[26] The first seep found on the CSZ, it has been named 'Pythia's Oasis', and may play a role in the regulation of overpressures.[27]
Some other subduction zones have major earthquakes every 100 to 200 years; the longer interval here may indicate unusually large stress buildup and subsequent unusually large earthquake slip.[28]
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.[29] However, recent investigations using radiocarbon dating and dendrochronology date the Bonneville landslide around 1450.[30][31][32]
See also
References
- ^ doi:10.7289/V5TD9V7K
- ^ Atwater et al. 2005, p. 98
- ISBN 978-0-295-98535-0.
- ^ S2CID 8305522.
- ^ a b c d Kathryn Schulz (July 20, 2015). "The Really Big One". The New Yorker.
- ^ a b "Jan. 26, 1700: How Scientists Know When The Last Big Earthquake Happened Here". Oregon Public Broadcasting, January 26, 2015.
- ^ "Ghosts of Tsunamis Past" Archived 2018-08-28 at the Wayback Machine. American Museum of Natural History.
- ^ doi:10.1785/gssrl.76.2.140, archived from the original(PDF) on 2015-07-24, retrieved 2015-07-24
- ^ "Tsunamis and Earthquakes – Native American Legends of Tsunamis in Pacific NW – USGS PCMSC".
- ^ a b c Meissner, Dirk (18 January 2015), "Earth will rip open like a zipper, expert says, when overdue Vancouver Island quake strikes", Toronto Star, retrieved 19 January 2015
- ^ "Prepare for next tsunami, says chief". Raven's Eye, Vol. 8, No. 9, 2009.
- Indian Country Today Media Network, December 16, 2014.
- ^ Indian Country Today Media Network, November 6, 2012.
- ^ "Get ready for the Big One". The Globe and Mail, April 22, 2011.
- doi:10.1130/b25189.1.
- ^ Yanev, Peter (27 March 2010). "Shake, Rattle, Seattle". The New York Times. p. WK11.
- ^ Schulz, Kathryn (20 July 2015). "The Really Big One". The New Yorker.
- ^ "A Major Earthquake in the Pacific Northwest Looks Even Likelier". The Atlantic. August 16, 2016.
- ^ "Odds Are 1-In-3 That A Huge Quake Will Hit Northwest In Next 50 Years". Oregon State University. 24 May 2010. Archived from the original on 27 May 2010. Retrieved 2010-05-24.
- ^ Oregon State University (May 25, 2010). "Odds are about 1-in-3 that mega-earthquake will hit Pacific Northwest in next 50 years, scientists say". ScienceDaily (Press release).
- ^ "Perilous Situation". The Oregonian. 2009-04-19. Archived from the original on 23 April 2009. Retrieved 2009-05-12.
- doi:10.1130/B25369.1.
- ^ Munro, Margaret (March 8, 2012). "Monster earthquake threat looms over B.C. coastal communities". Vancouver Sun. Archived from the original on February 3, 2019. Retrieved January 27, 2019.
- ^ "Coastal Washington tribe creates higher ground by building tsunami tower, first of its type here". Oregon Public Broadcasting. 2022-08-08. Archived from the original on 10 February 2023. Retrieved 2023-02-10.
- ^ "Here's Where the U.S. Is Testing a New Response to Rising Seas". The New York Times. 2022-11-02. Archived from the original on 10 February 2023. Retrieved 2023-02-10.
- ^ Hickey, Hannah (10 Apr 2023). "Warm liquid spewing from Oregon seafloor comes from Cascadia fault, could offer clues to earthquake hazards". UW News. Retrieved 13 April 2023.
- PMID 36696502.
- ^ "Cascadia Subduction Zone". Pacific Northwest Seismic Network.
- ^ Hill, Richard L. (2002-05-15). "Great Cascadia Earthquake Penrose Conference". The Oregonian. Archived from the original on 2008-10-24.
- S2CID 131976728. Archived from the originalon 2009-03-28. Retrieved 2009-09-07.
- ^ Pringle, Patrick T. (2009). "The Bonneville slide" (PDF). Columbia Gorge Interpretive Center Museum Explorations (Fall-Winter 2009): 2–3. Archived from the original (PDF) on 2018-01-05. Retrieved 2012-02-03.
- ^ "10,000 years of Cascadia earthquakes". The Oregonian. Retrieved June 11, 2019.
Further reading
- Melgar, Diego (2021). "Was the January 26th, 1700 Cascadia Earthquake Part of a Rupture Sequence?". Journal of Geophysical Research: Solid Earth. 126 (10). ISSN 2169-9313.
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
- Native American Legends of Tsunamis in Pacific NW – United States Geological Survey
- Fault slip and seismic moment of the 1700 Cascadia earthquake inferred from Japanese tsunami descriptions – Journal of Geophysical Research
- Japanese Shipwreck Adds To Evidence Of Great Cascadia Earthquake In 1700 – ScienceDaily
- Atwater, Brian F.; Musumi-Rokkaku, Satoko; Satake, Kenji; Tsuji, Yoshinobu; Ueda, Kazue; Yamaguchi, David K. (2015) [2005]. The orphan tsunami of 1700 – Japanese clues to a parent earthquake in North America (Professional Paper). Professional Paper (in English and Japanese) (2nd ed.). USGS. p. 146. ISBN 9780295985350.