Megathrust earthquake
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Megathrust earthquakes occur at
The thrust faults responsible for megathrust earthquakes often lie at the bottom of oceanic trenches; in such cases, the earthquakes can abruptly displace the sea floor over a large area. As a result, megathrust earthquakes often generate tsunamis that are considerably more destructive than the earthquakes themselves. Teletsunamis can cross ocean basins to devastate areas far from the original earthquake.
Terminology and mechanism
The term megathrust refers to an extremely large thrust fault, typically formed at the plate interface along a subduction zone, such as the Sunda megathrust.[4][5] However, the term is also occasionally applied to large thrust faults in continental collision zones, such as the Himalayan megathrust.[6] A megathrust fault can be 1,000 kilometers (600 mi) long.[7]
A thrust fault is a type of
Megathrust faults occur where two
Occurrence and characteristics
Megathrust earthquakes are almost exclusive to tectonic subduction zones and are often associated with the
Since these earthquakes deform the
In the Indian Ocean region, the Sunda megathrust is located where the Indo-Australian Plate subucts under the Eurasian Plate along a 5,500 kilometres (3,400 mi) fault off the coasts of Myanmar, Sumatra, Java and Bali, terminating off the northwestern coast of Australia. This subduction zone was responsible for the 2004 Indian Ocean earthquake and tsunami.[15]
In Japan, the Nankai megathrust under the Nankai Trough is responsible for Nankai megathrust earthquakes and associated tsunamis.[16] The largest megathrust event within the last 20 years was the magnitude 9.1 Tōhoku earthquake along the Japan Trench megathrust.[17]
In North America, the Juan de Fuca Plate subducts under the North American Plate, creating the Cascadia subduction zone from mid Vancouver Island, British Columbia down to Northern California. This subduction zone was responsible for the 1700 Cascadia earthquake.[18] The Aleutian Trench, of the southern coast of Alaska and the Aleutian Islands, where the North American Plate overrides the Pacific Plate, has generated many major earthquakes throughout history, several of which generated Pacific-wide tsunamis,[19] including the 1964 Alaska earthquake; at magnitude 9.2, it remains the largest recorded earthquake in North America, and the second-largest earthquake instrumentally recorded in the world.[20]
In the
A megathrust earthquake could occur in the Lesser Antilles subduction zone, with a maximum magnitude of 9.3, or potentially even 10.3 through recent evaluations, a value not considered impossible.[22]
The largest recorded megathrust earthquake was the
This megathrust region has regularly generated extremely large earthquakes.Geologists estimate that the largest possible earthquakes could have magnitudes of 10 to 11, most likely caused by a combined rupture of the Japan Trench and Kuril-Kamchatka Trench, or individually the Aleutian Trench or Peru–Chile Trench.[24][25][26] Another possible area could be the Lesser Antilles subduction zone.[22]
A study reported in 2016 found that the largest megathrust quakes are associated with downgoing slabs with the shallowest dip, so-called flat slab subduction.[27]
Compared with other earthquakes of similar magnitude, megathrust earthquakes have a longer duration and slower rupture velocities. The largest megathrust earthquakes occur in subduction zones with thick sediments, which may allow a fault rupture to propagate for great distances unimpeded.[5]
See also
References
- S2CID 206660652.
- ^ "Questions and Answers on Megathrust Earthquakes". Natural Resources Canada. Government of Canada. 19 October 2018. Retrieved 23 September 2020.
- ^ Johnston, Arch C.; Halchuk, Stephen (June–July 1993), "The seismicity data base for the Global Seismic Hazard Assessment Program", Annali di Geofisica, 36 (3–4): 133–151, pp. 140, 142 et seq.
- ISSN 0895-0695.
- ^ S2CID 133629102.
- doi:10.1038/ngeo2623.
- ^ a b "Cascadia Subduction Zone". Pacific Northwest Seismic Network. Retrieved 7 October 2021.
- ^ "Earthquake Glossary – dip slip". Earthquake Hazards Program. U.S. Geological Survey.
- ISBN 9781107057647.
- ^ "Tsunami Terminology". The National Tsunami Hazard Mitigation Program History, 1995–2005. Pacific Marine Environmental Laboratory. Archived from the original on 2011-02-25.
- ^ Fossen 2016, p. 356.
- ^ "What is the Ring of Fire?". Ocean exploration. National Ocean and Atmospheric Administration. Retrieved 7 October 2021.
- PMID 28378757.
- .
- .
- ^ Hirahara, K.; Kato N.; Miyatake T.; Hori T.; Hyodo M.; Inn J.; Mitsui N.; Sasaki T.; Miyamura T.; Nakama Y.; Kanai T. (2004). "Simulation of Earthquake Generation Process in a Complex System of Faults" (PDF). Annual Report of the Earth Simulator Center April 2004 - March 2005. pp. 121–126. Archived from the original (PDF) on 2011-09-27. Retrieved 2009-11-14.
- ^ "M 9.1 - 2011 Great Tohoku Earthquake, Japan". Earthquake Hazards Program. United States Geological Survey. 7 November 2016. Retrieved 3 June 2022.
- ^ "A Major Earthquake in the Pacific Northwest Looks Even Likelier". The Atlantic. August 16, 2016.
- S2CID 134362013.
- .
- ISSN 0094-8276.
- ^ ISSN 1680-7340.
- S2CID 216347638.
- ^ Kyodo (2012-12-15). "Magnitude 10 temblor could happen: study". The Japan Times. Retrieved 2023-10-20.
- .
- ISSN 0956-540X.
- PMID 27885027. Retrieved 2018-06-05.
Further reading
External links
- ISSN 0040-1951.