1585 Aleutian Islands earthquake

Source: Wikipedia, the free encyclopedia.
1585 Aleutian Islands earthquake
Megathrust
Areas affectedHawaii, Alaska
Sanriku, Japan
TsunamiYes
CasualtiesMany native people in Hawaii killed

The 1585 Aleutian Islands earthquake is the presumed source of a

moment magnitude
(Mw ) as large as 9.25.

Background

In 1586, a legend emerged in Japan describing a wave measuring up to two meters which struck near Tokura village in the Motoyoshi District of Miyagi Prefecture.[1] Surviving historical accounts from the period are ambiguous or incomplete, which has made it difficult to identify the tsunami's specific origin. The tsunami was dubbed the "orphan tsunami" or "ghost tsunami" due to the uncertainties regarding the event.

Tsunami event

According to Kenji Satake, a Japanese seismologist, the legend of the 1586 tsunami should be disregarded because it was a false event. There was no historical documentation of a tsunami striking the Sanriku coast in that year.[2]

In the aftermath of the deadly

megathrust. Historical descriptions of the tsunami that struck locally in Callao reported two very different heights, 3.7 meters and 24 meters.[3] The latter was determined to be an exaggeration of the tsunami height after much evaluation;[4] a more accurate estimate for the 1586 Peru tsunami is 5 meters.[5] Further modelling of the Peru tsunami by a group of researchers in 2006 was unsuccessful in accurately matching the historical descriptions of the wave heights in Peru and Japan.[6][4] Large tsunamis originating in Chile have been reported in Japan due to the orientation of the tsunami source, but Peru-sourced tsunamis are usually weaker because they are not directed towards Japan, suggesting that the claim of a Peru tsunami causing the 1586 event in Japan is incorrect.[7]

In another tsunami catalog compiled after the 1933 Sanriku earthquake, the author referenced a 1903 publication which stated that a tsunami occurred on 11 June 1585, or Tensho 13th year, 5th month and 14th day. Meanwhile, another tsunami event on 18 January 1586, was recorded, possibly associated with the 1586 Tenshō earthquake (ja). Because the Tenshō earthquake occurred in 1586, the Sanriku tsunami was incorrectly dated to 1586, coincidentally matching the Peru quake as well.[7]

Hawaiian culture

The

Kāne‘ohe Bay on the island of Oahu. Archaeological and historical evidences showed that the tsunami occurred sometime between 1040 and 1280 A.D.[8]

A chant composed between 1500 and 1600 described a tsunami-like event occurring on the western coast of Molokai. The chant is believed to be the oldest record of a tsunami in Hawaii.

"The sun shines brightly at Kalaeola which sank into the sea. A huge wave came and killed its inhabitants, scattering them and leaving only Papala'au; their cries are all about.[9]"

Future threat

At least 24 to 40 meters of slip has been accumulated since the earthquake of 1585 and it is possible for another event of a similar magnitude to occur. If a tsunami was generated, it would require just 4.5 hours of travel time to reach the Hawaiian Islands.[10]

Evidence

Hawaii

A study of the northwestern coast of

Kaua‘i in 2002 discovered evidence of a large tsunami in a layer of buried sand, similar to the tsunami deposits found after the 1946 earthquake.[11]

The Makauwahi Cave where there is evidence of a major tsunami-like event in the 16th century.

Earlier in 2001, at Makauwahi Sinkhole in the

cobbles, gravel, and sand, severely fractured and angular, concluded that they formed during one intense event.[12]
Dating of the deposits presented a time period of 1430–1665 A.D..

In a 2014 study of the site led by Rhett Butler, researchers from the

mean sea level, and location of the sinkhole 100 meters from the coast. The deposit volume is also estimated to be 600 cubic meters.[8]

Based on the location in which the deposit was found, the tsunami must be a very significant event. The layer deposited in the sinkhole was sourced by a tsunami much larger than anything generated by the largest Pacific earthquakes. The largest run-up height in modern times was from the 1960 Valdivia earthquake which tsunami run-up measured 3 meters. None of the recent tsunamis have been able to reach and inundate the Makauwahi Sinkhole, which lies 7.2 meters above sea level at a distance of 100 meters from the shore.[8]

Another research in 2017 revisited the site of the sinkhole to radiocarbon date plant materials in the deposit and found that the tsunami inundation occurred between 1425 and 1660 A.D.[10] Together with the required tsunami run-up heights, the tsunami may have been associated with the misdated Sanriku tsunami of 1586.

Elsewhere

The Sanriku orphan tsunami may have been associated with deposited materials in near Sendai City, Miyagi, which could not be explained by nearby earthquakes.[10][13] Inscriptions on a monument at Tokura village said that the tsunami struck the northeastern coast of Japan with a height of 1 to 2 meters.[10]

There is paleotsunami evidence in nine locations in Oregon, Washington and British Columbia to show that a tsunami occurred near the Cascadia subduction zone prior to the 1700 event. The next prior event in Cascadia was a less energetic tsunami event inferred to have taken place between 1402 and 1502, with an uncertainty of ± 20 years. This rules out Cascadia as the cause of the 1585 tsunami. Dating of the event however, strongly supported the Aleutian Islands as being the tsunami source.[14]

The closest known historical earthquakes from 1585 to 1586 were the 1604 Arica, 1587 Guayllabamba and 1575 Valdivia earthquakes, which all generated tsunamis along the South American coast. However, no tsunamis from these events were ever measured on the Japanese coasts.[10]

Sedanka Island from space

Paleotsunami studies on Sedanka Island near Amaknak Island found five large tsunami events before 1957. One of these tsunami deposits was found up to one kilometer inland and up to 18 meters above sea level. This tsunami event has been dated at 1530–1665 A.D.[15][16]

Earthquake

Aleutian-Alaska megathrust
, source of the 1585 earthquake and tsunami

The Aleutian Islands lie near a

megathrust earthquakes, sometimes tsunamigenic. The 1946 Aleutian Islands earthquake and 1964 Alaska earthquake, measuring 8.6 Mw  and 9.2 Mw  respectively, are examples of earthquakes on the subduction zone; both resulted in devastating tsunamis.[17][18]

In the same 2014 study led by Butler, researchers simulated the tsunami from a 9.25 Mw earthquake in the eastern Aleutian Islands, west of the earthquake rupture. The rupture area is 100 km by 600 km with an average slip of 35 meters on the megathrust.[8] Their model was found to be sufficient enough to inundate the sinkhole. Along the Pacific Northwest coast, the tsunami measured a maximum of 9 meters while the mean height was 3.5 meters.[10] The orientation of the megathrust with respect to the Hawaiian Islands allowed for much directivity of the tsunami energy. The results of the model did not rule out the possibility of other distant tsunami source locations. However, such events would have to greatly exceed the fault slip seen in other historically large events.[8]

See also

References

  1. doi:10.7289/V5PN93H7
    . Retrieved 8 July 2021.
  2. CiteSeerX 10.1.1.723.1716
    .
  3. S2CID 140620121
    .
  4. ^
    Bibcode:2017AGUFMNH12A..08S
    . Retrieved 8 July 2021.
  5. ^ L. Dorbath; A. Cisternas; C. Dorbath (1990). "Assessment of the size of large and great historical earthquakes in Peru". Bulletin of the Seismological Society of America. 80: 551–576. Retrieved 8 July 2021.
  6. ^ Kumiji Iida; Doak C Cox (1967). George Pararas-Carayannis (ed.). "PRELIMINARY CATALOG OF TSUNAMIS OCCURRING IN THE PACIFIC OCEAN" (PDF). Hawaii Institute of Geophysics. 67-10 (5). University of Hawaii.
  7. ^
    S2CID 212778611
    . Retrieved 8 July 2021.
  8. ^
    doi:10.1002/2014GL061232
    .
  9. ^ James F. Lander; Patricia A. Lockridge (1989). United States Tsunamis: (including United States Possessions) : 1690-1988. Boulder, Colorado: U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, Data, and Information Service, National Geophysical Data Center. p. 265.
  10. ^
    S2CID 134237666
    .
  11. doi:10.1017/S003382220006464X
    .
  12. doi:10.1890/0012-9615(2001)071[0615:FEFADB]2.0.CO;2
    . Retrieved 9 July 2021.
  13. S2CID 55355007
    . Retrieved 9 July 2021.
  14. doi:10.1016/j.sedgeo.2007.01.015
    . Retrieved 9 July 2021.
  15. Bibcode:2013AGUFMNH44A..08W. Retrieved 9 July 2021.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  16. S2CID 131231692.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  17. ^ "M 8.6 - 1946 Aleutian Islands (Unimak Island) Earthquake, Alaska". earthquake.usgs.gov. USGS. Retrieved 9 July 2021.
  18. ^ "M 9.2 - 1964 Prince William Sound Earthquake, Alaska". earthquake.usgs.gov. USGS. Retrieved 9 July 2021.

Further reading

  • Yutaka Hayashi; Masashi Kiyomoto; Yuji Nishimae; Go Tange (28 March 2018). "気象庁技術報告に含まれた 1586 年ペルー沖の地震による" [Negative Effects of Erroneous Records of Japanese Tsunami Caused by the 1586 Earthquake off the Coast of Peru Being Included in the Technical Reports of the Japan Meteorological Agency] (PDF). Quarterly Journal of Seismology 2017 (in Japanese). 81 (9).
Retrieved from "https://en.wikipedia.org/w/index.php?title=1585_Aleutian_Islands_earthquake&oldid=1210884350"