Causes of tsunamis in the Pacific Ocean

The terrifying combination of geological and geographic factors has made the Samoa Islands people have no chance to escape the tsunami on September 29.

The epicenter of the earthquake has an intensity of 8 to 8.3 on the Richter scale at 1:48 am Hanoi in the Pacific Ocean is located just below the ocean floor, meaning its power is very little lost. Furthermore, seismic recession occurs at a very large depth compared to the seabed (about 18 km), which can cause extremely large waves and spread faster in the ocean. American Samoa's position is quite close to the epicenter (about 200 km), so shallow water on the surface of the ocean is not strong enough to block the tsunami from below. Usually the speed of tsunamis decreases when colliding with shallow water layers.

A car stuck on the wall of a building in the port of Pago Pago of American Samoa after the September 29 tsunami.(Photo: Reuters) .

All of these factors caused the first tsunami to rise about 13 minutes after the ground shook and attacked the Samoa Islands. During that time, the computer system of the Pacific Tsunami Warning Center (Hawaii, USA) had a problem that prevented experts from giving a timely tsunami warning.

" This is an earthquake that is capable of destroying areas near the epicenter and unfortunately it happens near the Samoa Islands ," AP news agency quoted Stuart Weinstein, deputy director of the Thai Tsunami Warning Center. Binh Duong, said.

After the office of the weather forecast office in the American capital of Pago Pago shook, a local official immediately phoned the Pacific Tsunami Warning Center. Meanwhile, the head of the weather forecast agency contacted the US Department of Homeland Security to activate the tsunami warning system. Before 7:00 am on September 29, local time, warnings are posted on television channels and radio stations.

Rescue workers carried the body of a girl they found in the port of Pago Pago after the tsunami.(Photo: Reuters) .

But all those measures are taken too late. 4 tsunamis as high as 4.5-6 m over the coast at speeds of up to 848 km / h (equivalent to the speed of Boeing 747). The speed of waves when touching the mainland is 50 km / h. That means that if someone sees a tsunami, that person won't be able to escape. As of today, the total number of deaths has exceeded 120.

Tsunamis are high waves caused by earthquakes. Their height can be up to 30m. Tsunamis can hit the shore in about an hour, withdrawing to the sea very quickly and then returning several hours later. If there are some more favorable conditions, the tsunami yesterday could become a more catastrophic disaster than the tsunami that killed more than 150,000 people in Asia in 2004.