Tsunami risk in the West Coast of the United States

The likelihood of a massive tsunami from the Pacific to the west coast of the United States may be larger than previously thought, according to a new study of geological evidence along the Gulf of Alaska.

The new study shows that future tsunamis will reach a much greater degree than tsunamis in 1964 due to reaching in Alaska. Official figures for the number of deaths from earthquake events in 1964 were 130: 114 people in Alaska and 16 people in Oregon and California. The tsunami directly killed 35 people and caused much damage in Alaska, British Columbia, and the US Pacific region.

Alaska earthquake in 1964 - the second largest earthquake in history with a magnitude of 9.2 - created a series of huge waves of up to 12.7 meters in the Gulf of Alaska and 52 meters in Gulf of Shoup at Valdez Arm.

The study found that fractures with a larger area than the cracked area in 1964 could create a much larger tsunami. The warning system is already available in the West Coast but findings suggest that there is still a need to review evacuation plans in this area.

The team from Durham University, England, the University of Utah and Plafker Geohazard Consulting, measured the scale of the earthquakes over the past 2000 years using specimens from the soil layer and sediments at locations along the Alaskan coast. The team used radioactive carbon methods to date peat and sediment layers, and analyze the distribution of mud, sand, and peat inside. The results show that earthquakes in this area could break a larger range of coastlines and seabeds than previously thought.

The study was published in Quaternary Science Reviews and funded by the National Science Foundation, NASA and the US Geographic Survey. The results show that the potential impact of the generated tsunami may be significantly larger than that of the 80km long section in 1964, and the adjacent Yakataga section of 250 km long cracking at the same time.

The main author, Professor Ian Shennan, from Durham University Geography Department, said: 'Our samples show that the area affected by the previous earthquakes was 15% larger than the yearly event. 1964. Historical evidence of stratigraphic fractures on a large scale and at the same time in the Alaska region is important for tsunami capabilities of the Gulf of Alaska and the Pacific region. '

'Peat layers provide a clear picture of what happened. Our data indicate that two major earthquakes occurred in Alaska in the past 1500, and the findings show a larger earthquake and a devastating tsunami than the 1964 incident is something that can happen in the future. The area has suffered a massive earthquake with previous tsunamis, and our evidence indicates that more and wider cracks may occur. '

Sitka, Alaska. The likelihood of a massive tsunami from the Pacific to the west coast of the United States may be larger than previously thought, according to a new study of geological evidence along the Gulf of Alaska. (Photo: iStockphoto / Brandon Laufenberg)

Tsunamis can be generated by the movement of water currents quickly when the sea floor rises or subsides due to the movement of the Earth's crust attached to earthquakes.The shallow nature of the seabed off Alaska can increase the devastation of a Pacific tsunami. The earthquake is difficult to predict in this area, where the transition between the two strata, the Fairweather fault, and the Aleutian neighborhood. In 1899 and 1979, large earthquakes appeared in the area but did not form tsunamis because the fracture was located underground but not the sea floor.

Professor Ron Bruhn from the University of Utah said: 'If a larger earthquake occurs in this area, the size of the tsunami will be significantly larger than in 1964, because the earthquake is cracking. can shift the shallow continental shell of Yakutat sub-strata.

'In case of many cracks, the energy transmitted to the tsunami will be larger and the tsunami will go further. In addition to small communities near the tsunami source, further areas such as Southeastern Alaska, British Columbia, and the western US coast from Washington to California will also be affected. '

The warning system is ready in the United States and Hawaii's west coast from the Aleutian Islands tsunami in 1946. There have been significant improvements after the 2004 Indian Ocean earthquake that caused a tsunami. The most terrible in history, taking away the lives of more than 230,000 people. Professor Shennan said: 'Earthquakes can happen at any time of the day or night, and it is a big challenge for emergency planners. A tsunami in this area can cause enormous damage to people and from Alaska to California and beyond; in 1964 the impact of tsunamis spread to Southern California. '

Dr George Plafker of Plafker Geohazard Consulting said: 'A big earthquake is not necessarily a big wave. The height of the tsunami depends on the depth of the sea, and the number of slides and subsidence of the faults, and all of these factors vary considerably according to the wave '.

'Tsunami will appear in the future. There are many problems with reporting and evacuating a large number of people quickly and safely. The United States has a very good warning system but its awareness is limited. '