Aleutian Trench: Difference between revisions
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The north side of the trench slopes 3°–4° and the south side 1°–4°.<ref>{{cite web | url=http://gsabulletin.gsapubs.org/content/56/7/757 | title=Profile of Aleutian Trench | accessdate=May 6, 2012}}</ref> The deepest part of the Aleutian trench has been measured at {{Convert|7822|m|ft|0}} at 51.21°N, 174.83°E.,<ref name="NOAA Chart 513">{{cite web|url=http://www.charts.noaa.gov/OnLineViewer/513.shtml|title=North Pacific Ocean Bering Sea (Southern Part) |date=June 2004 |work=NOAA Chart 513 7th Edition|accessdate=29 November 2012}}</ref> located about 145 km SSW of [[Buldir]] Island. |
The north side of the trench slopes 3°–4° and the south side 1°–4°.<ref>{{cite web | url=http://gsabulletin.gsapubs.org/content/56/7/757 | title=Profile of Aleutian Trench | accessdate=May 6, 2012}}</ref> The deepest part of the Aleutian trench has been measured at {{Convert|7822|m|ft|0}} at 51.21°N, 174.83°E.,<ref name="NOAA Chart 513">{{cite web|url=http://www.charts.noaa.gov/OnLineViewer/513.shtml|title=North Pacific Ocean Bering Sea (Southern Part) |date=June 2004 |work=NOAA Chart 513 7th Edition|accessdate=29 November 2012}}</ref> located about 145 km SSW of [[Buldir]] Island. |
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Center pressure: {{convert|10762|psi|atm MPa}}.<ref>{{cite web |
Center pressure: {{convert|10762|psi|atm MPa}}.<ref>{{cite web|url=http://www.wolframalpha.com/entities/undersea_features/aleutian_trench/q0/nf/c7/ |title=Aleutian Trench Data |accessdate=May 6, 2012 }}{{dead link|date=June 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Variations in total magnetic intensity (residual) of more than 600 γ (600 [[nanotesla]]s) were found in the center of the trench and more than 1100 γ on the southern flank.<ref>{{cite web | url=http://www.agu.org/pubs/crossref/1965/JZ070i002p00353.html | title=Magnetic Information | accessdate=May 6, 2012}}</ref> |
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==Associated seismicity== |
==Associated seismicity== |
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The [[Subduction zone|subduction]] of the [[Pacific Plate]] below the [[North American Plate]] along the Aleutian Trench is associated with numerous earthquakes. Several of these earthquakes are notable for their size and/or associated tsunamis. |
The [[Subduction zone|subduction]] of the [[Pacific Plate]] below the [[North American Plate]] along the Aleutian Trench is associated with numerous earthquakes. Several of these earthquakes are notable for their size and/or associated tsunamis. |
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*April 1, [[1946 Aleutian Islands earthquake]]: This [[Richter magnitude scale|magnitude]] 8.1 earthquake occurred offshore [[Unimak Island]],<ref>[http://earthquake.usgs.gov/earthquakes/states/events/1946_04_01.php USGS - Historic Earthquakes, Unimak Island]</ref> and caused only minor damage on land. However, the shaking generated a tsunami which killed 5 on the island and caused damage on other Aleutian Islands and North and South America. In [[Hilo, Hawaii]], the tsunami killed 159 and caused extensive damage. |
*April 1, [[1946 Aleutian Islands earthquake]]: This [[Richter magnitude scale|magnitude]] 8.1 earthquake occurred offshore [[Unimak Island]],<ref>[http://earthquake.usgs.gov/earthquakes/states/events/1946_04_01.php USGS - Historic Earthquakes, Unimak Island] {{webarchive|url=https://web.archive.org/web/20130731091632/http://earthquake.usgs.gov/earthquakes/states/events/1946_04_01.php |date=2013-07-31 }}</ref> and caused only minor damage on land. However, the shaking generated a tsunami which killed 5 on the island and caused damage on other Aleutian Islands and North and South America. In [[Hilo, Hawaii]], the tsunami killed 159 and caused extensive damage. |
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*March 9, [[1957 Andreanof Islands earthquake]]: This [[Richter magnitude scale|magnitude]] 8.6<ref>[http://earthquake.usgs.gov/earthquakes/states/events/1957_03_09.php USGS - Historic Earthquakes, 1957 Andreanof Islands]</ref> earthquake occurred south of the [[Andreanof Islands]]. The earthquake itself caused damage on [[Adak Island]] and [[Umnak Island]] and generated a Pacific-wide tsunami. The tsunami caused extensive damage in Scotch Cap on [[Unimak Island]], including the destruction of the [[Scotch Cap Light]], and destroyed two villages in the [[Hawaiian Islands]]. The tsunami was recorded as far away as Chile.<ref>[http://www.usc.edu/dept/tsunamis/alaska/ USC Tsunami Research Group]</ref> |
*March 9, [[1957 Andreanof Islands earthquake]]: This [[Richter magnitude scale|magnitude]] 8.6<ref>[http://earthquake.usgs.gov/earthquakes/states/events/1957_03_09.php USGS - Historic Earthquakes, 1957 Andreanof Islands]</ref> earthquake occurred south of the [[Andreanof Islands]]. The earthquake itself caused damage on [[Adak Island]] and [[Umnak Island]] and generated a Pacific-wide tsunami. The tsunami caused extensive damage in Scotch Cap on [[Unimak Island]], including the destruction of the [[Scotch Cap Light]], and destroyed two villages in the [[Hawaiian Islands]]. The tsunami was recorded as far away as Chile.<ref>[http://www.usc.edu/dept/tsunamis/alaska/ USC Tsunami Research Group]</ref> |
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*February 4 [[1965 Rat Islands earthquake]]: This [[Richter magnitude scale|magnitude]] 8.7 earthquake triggered a [[tsunami]] that struck [[Shemya Island]] and was observed around the Pacific, but caused little damage. |
*February 4 [[1965 Rat Islands earthquake]]: This [[Richter magnitude scale|magnitude]] 8.7 earthquake triggered a [[tsunami]] that struck [[Shemya Island]] and was observed around the Pacific, but caused little damage. |
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Revision as of 17:03, 30 June 2017
The Aleutian Trench (or Aleutian Trough)[1] is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for 3,400 km from a triple junction in the west with the Ulakhan Fault and the northern end of the Kuril–Kamchatka Trench, to a junction with the northern end of the Queen Charlotte Fault system in the east. It is classified as a "marginal trench" in the east as it runs along the margin of the continent. The subduction along the trench gives rise to the Aleutian arc, a volcanic island arc, where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. Here, the Pacific Plate is being subducted under the North American Plate at a dip angle of nearly 45°. The rate of closure is 3 inches (76 mm) per year.[2]
Trench morphology
The north side of the trench slopes 3°–4° and the south side 1°–4°.[3] The deepest part of the Aleutian trench has been measured at 7,822 metres (25,663 ft) at 51.21°N, 174.83°E.,[4] located about 145 km SSW of Buldir Island.
Center pressure: 10,762 pounds per square inch (732.3 atm; 74.20 MPa).[5] Variations in total magnetic intensity (residual) of more than 600 γ (600 nanoteslas) were found in the center of the trench and more than 1100 γ on the southern flank.[6]
Associated seismicity
The subduction of the Pacific Plate below the North American Plate along the Aleutian Trench is associated with numerous earthquakes. Several of these earthquakes are notable for their size and/or associated tsunamis.
- April 1, 1946 Aleutian Islands earthquake: This magnitude 8.1 earthquake occurred offshore Unimak Island,[7] and caused only minor damage on land. However, the shaking generated a tsunami which killed 5 on the island and caused damage on other Aleutian Islands and North and South America. In Hilo, Hawaii, the tsunami killed 159 and caused extensive damage.
- March 9, 1957 Andreanof Islands earthquake: This magnitude 8.6[8] earthquake occurred south of the Andreanof Islands. The earthquake itself caused damage on Adak Island and Umnak Island and generated a Pacific-wide tsunami. The tsunami caused extensive damage in Scotch Cap on Unimak Island, including the destruction of the Scotch Cap Light, and destroyed two villages in the Hawaiian Islands. The tsunami was recorded as far away as Chile.[9]
- February 4 1965 Rat Islands earthquake: This magnitude 8.7 earthquake triggered a tsunami that struck Shemya Island and was observed around the Pacific, but caused little damage.
- May 7, 1986 Andreanof Islands earthquake: This magnitude 7.9 earthquake caused damage on Adak Island and Atka Island. The resultant tsunami was recorded throughout the Pacific.[10]
- On June 23, 2014, a 7.9 quake occurred near Little Sitkin Island, Alaska.
References
- ^ Webster's New Geographical Dictionary. Springfield, Massachusetts: Merriam-Webster Inc. 1984. p. 30. ISBN 0-87779-446-4.
- ^ "Aleutian Trench". Archived from the original on February 25, 2014. Retrieved May 4, 2012.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ "Profile of Aleutian Trench". Retrieved May 6, 2012.
- ^ "North Pacific Ocean Bering Sea (Southern Part)". NOAA Chart 513 7th Edition. June 2004. Retrieved 29 November 2012.
- ^ "Aleutian Trench Data". Retrieved May 6, 2012.[permanent dead link]
- ^ "Magnetic Information". Retrieved May 6, 2012.
- ^ USGS - Historic Earthquakes, Unimak Island Archived 2013-07-31 at the Wayback Machine
- ^ USGS - Historic Earthquakes, 1957 Andreanof Islands
- ^ USC Tsunami Research Group
- ^ USGS - Historic Earthquakes