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| UTC time | 1965-02-04 05:01:22 |
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| ISC event | 859206 |
| USGS-ANSS | ComCat |
| Local date | February 3, 1965 (1965-02-03) |
| Local time | 19:01:22 |
| Magnitude | 8.7 Mw |
| Depth | 30.3 km (19 mi) |
| Epicenter | 51°17′N 178°33′E / 51.29°N 178.55°E / 51.29; 178.55 |
| Areas affected | United States (Alaska) |
| Total damage | $10,000 |
| Max. intensity | MMI VI (Strong) |
| Tsunami | 10.7 m (35 ft) |
The 1965 Rat Islands earthquake occurred at 05:01 UTC, on 4 February (19:01, 3 February local time). It had a magnitude of 8.7 and triggered a tsunami of over 10 m on Shemya Island, but caused very little damage.
Tectonic setting
The Rat Islands form part of the Aleutian Islands, a chain of volcanic islands forming an island arc, that results from the subduction of the Pacific plate beneath the North American plate. This plate boundary, the Aleutian Trench, has been the location of many megathrust earthquakes.
Characteristics
The 1965 Rat Islands earthquake share common features with the 1963 Kuril Islands earthquake and the 1964 Alaska earthquake.
Earthquake
The earthquake was associated with a 600 km long rupture along the plate boundary, based on the distribution of aftershocks. The pattern of energy release suggest the presence of three asperities along the plate interface, each causing a pulse of moment release. Modelling of the tsunami supports the idea that the earthquake consisted of three sub-events, related to three structural 'blocks' within the overriding plate.
The main shock was followed by an earthquake of magnitude 7.6 nearly two months later, that triggered a small tsunami. This was not an aftershock, but a normal fault event within the outer rise of the subducting plate, triggered by the earlier event.
Tsunami
The tsunami had a maximum run-up height of 10.7 m on Shemya Island, 2.0 m at Amchitka Island, 1.6 m at Attu Island and 1.1 m in northern Kauai, Hawaii. It was also observed in Peru, Ecuador, Mexico, California, Japan and eastern Russia.
Damage
Flooding from the tsunami caused $10,000 worth of damage on Amchitka Island. Minor damage from the earthquake was recorded on both Attu and Shemya islands in the form of cracks in runways.
See also
- 2021 Chignik earthquake
- List of earthquakes in 1965
- List of earthquakes in Alaska
- List of earthquakes in the United States
References
- ^ NGDC. "Search result for 1965 Alaska earthquakes". Archived from the original on December 30, 2017. Retrieved 8 March 2010.
- ^ "Historic Earthquakes Rat Islands, Alaska". United States Geological Survey. 26 October 2009. Archived from the original on 16 January 2010. Retrieved 8 March 2010.
- Wu, Francis T.; Kanamori, Hiroo (9 October 1973). "Source mechanism of February 4, 1965, Rat Island earthquake". Journal of Geophysical Research. 78 (26): 6082–6092. Bibcode:1973JGR....78.6082W. doi:10.1029/jb078i026p06082.
- Beck, Susan L.; Christensen, Douglas H. (1991). "Rupture process of the February 4, 1965, Rat Islands Earthquake". Journal of Geophysical Research. 96 (B2): 2205. Bibcode:1991JGR....96.2205B. doi:10.1029/90JB02092.
- Johnson, Jean M. (1998). "Heterogeneous Coupling Along Alaska-Aleutians as Inferred from Tsunami, Seismic, and Geodetic Inversions". Tsunamigenic Earthquakes and Their Consequences. Advances in Geophysics. Vol. 39. pp. 1–116. doi:10.1016/S0065-2687(08)60275-7. ISBN 978-0-12-018839-0.
- Abe, Katsuyuki (January 1972). "Lithospheric normal faulting beneath the Aleutian trench". Physics of the Earth and Planetary Interiors. 5: 190–198. Bibcode:1972PEPI....5..190A. doi:10.1016/0031-9201(72)90091-X.
Further reading
- Jordan, James N.; Lander, James F.; Black, Rudolph A. (1965). "Aftershocks of the 4 February 1965 Rat Island Earthquake". Science. 148 (3675): 1323–1325. Bibcode:1965Sci...148.1323J. doi:10.1126/science.148.3675.1323. JSTOR 1716000. PMID 17791261. S2CID 11528694.
External links
- The International Seismological Centre has a bibliography and/or authoritative data for this event.
| ← Earthquakes in 1965 → | |
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| † indicates earthquake resulting in at least 30 deaths ‡ indicates the deadliest earthquake of the year |
| Earthquakes in Alaska | |
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