However, the shaking generated a tsunami which killed 5 US Coast Guard personnel on the island, destroying the Scotch Cap Light, and causing damage on other Aleutian Islands and North and South America. ApAleutian Islands earthquake: This magnitude 8.6 earthquake occurred offshore Unimak Island, and caused only minor damage on land.Modelling of a tsunami from an earthquake of 9.25 M w in the Aleutian Islands proved consistent with the descriptions and paleotsunami evidences. Oral records from the native residents described a tsunami-like event killing many people. Evidence of a large tsunami in the 16th century was also discovered in the Hawaiian Islands in the form of deposits. June 10–11, 1585 Aleutian Islands earthquake: A misdated tsunami legend in the Sanriku coast of Japan was dismissed and inferred to be from a vaguely–documented tsunami event in Miyagi Prefecture on June 11, 1585.Several of these earthquakes are notable for their size and/or associated tsunamis. The subduction of the Pacific Plate below the North American Plate along the Aleutian Trench is associated with numerous earthquakes. 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. The deepest part of the Aleutian trench has been measured at 7,822 metres (25,663 ft) at 51.21°N, 174.83☎., located about 145 kilometres (90 mi) SSW of Buldir Island.Ĭenter pressure: 10,762 pounds per square inch (732.3 atm 74.20 MPa). The north side of the trench slopes 3°–4° and the south side 1°–4°. The rate of closure is 7.5 centimetres (3 in) per year. Here, the Pacific Plate is being subducted under the North American Plate at a dip angle of nearly 45°. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. 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. It is classified as a 'marginal trench' in the east as it runs along the margin of the continent. The trench extends for 3,400 kilometres (2,100 mi) 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 also the largest quake in North America since an Alaskan quake of 8.7 magnitude in 1965, according to USGS data.The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The quake was the seventh largest in US history, tied with another Alaskan quake from 1938, according to USGS data. The Pacific Tsunami Warning Centre (PTWC) cancelled warnings issued for Hawaii and the US Pacific territory of Guam, while the public broadcaster NHK said there was no risk to Japan.Īuthorities in New Zealand also said they did not expect any flooding in coastal areas.Īccording to the USGS, the quake was followed by over 25 aftershocks in the region, with two around magnitude 6.0. “That’s really fortunate in this case, because 8.2 is really strong enough to make a sizable wave, especially in that location of the world,” Snider added. While shallow earthquakes near populated areas can be dangerous, in this case the shallow quake posed less of a threat because they do not usually generate large tsunamis. “There might be some minor damage in some places (in Alaska), but a significant tsunami and significant damage from something like that is not expected,” Snider said.

The US states of California, Oregon and Washington and the Canadian province of British Columbia were not expected to see any significant tsunami threats, Dave Snider, tsunami warning coordinator with the NTWC, told Reuters. It struck about 91 km east-southeast of Perryville, about 800 km (500 miles) from Anchorage, Alaska’s biggest city. The US Geological Survey (USGS) said the quake, which struck at 10:15 pm local time (0615 GMT Thursday), was at a depth of 35 km. Among them was Seward on the Kenai Peninsula, south of Anchorage, where sirens blared and residents were told to move to higher ground. Several Alaskan coastal communities were evacuated following the quake. There were no immediate reports of injuries or damage to property. In Alaska, small tsunami waves measuring under a foot above tide level were observed in Sand Point, Old Harbor, King Cove, Kodiak, Unalaska and Alitak Bay, according to the US National Tsunami Warning Centre (NTWC). Tsunami warnings were lifted for Alaska and the rest of Pacific after a huge earthquake of 8.2 magnitude struck the seismically active US state in the late hours on Wednesday.

Alaska quake depth