Risk of earthquake and tsunami may affect Vietnam

After the tsunami disaster in Indonesia, many people are concerned that earthquakes and tsunamis may affect Vietnam. According to research results conducted at the Institute of Geophysics, earthquake sources in the East Sea and neighboring areas can cause tsunamis affecting our country's coastline. Discovery Magazine would like to quote part of an article by Dr. Le Huy Minh, Director of the Earthquake Information and Tsunami Warning Center and Dr. Nguyen Hong Phuong, Deputy Director of the Center about this risk.

Earthquake risk

Vietnam is located in the Southeast part of the Eurasian Plate, between the Indian Plate, the Philippine Plate and the Australian Plate. Vietnam's territory is not located on the edge of the plates, so it is less vulnerable to earthquakes than other countries in the region such as Indonesia, the Philippines and Malaysia.

But in Vietnam's territory and territorial waters, there exists a complex system of active faults such as: Lai Chau - Dien Bien fault, Song Ma fault, Son La fault, Red River fault zone, Ca River fault zone, 109-110 meridian fault.^o…, so earthquakes also occur frequently.

Tectonic seismic map of Vietnam and neighboring areas.

Since the beginning of the 20th century, the Northern region has had two earthquakes of magnitude 8-9 (6.7-6.8 on the Richter scale), dozens of earthquakes of magnitude 7 (5.1-5.5 on the Richter scale) and hundreds of weaker earthquakes. A typical example is the 1935 Dien Bien earthquake of magnitude 6.75 on the Song Ma fault zone.

More recently, the 2001 Dien Bien earthquake, measuring 5.3 on the Richter scale, with its epicenter in Laos, about 20 km from Dien Bien city, caused light damage to the collapse of more than 2,000 houses in the Dien Bien city area.

From 2007 to now, many earthquakes with magnitudes less than 5.5 on the Richter scale have occurred in Vietnam, such as the earthquake off the coast of Vung Tau - Phan Thiet on November 28, 2007 (5.1 on the Richter scale); the earthquake in Do Luong on January 3, 2008 (3.8 on the Richter scale)...

The small earthquakes that occurred after the Dien Bien earthquake did not cause any damage to people or property. However, they also showed that the Earth's crust in the Vietnam area is not completely stable. Earthquakes need to be monitored and studied to have a more and more complete assessment of seismic activity in Vietnam, actively serving the country's construction.

Tsunami risk

Up to now, there has been no convincing evidence to confirm that tsunamis have affected the coast of Vietnam. However, according to research results conducted at the Institute of Geophysics, earthquake source areas in the East Sea and neighboring areas that can cause tsunamis affecting the coast of Vietnam include: Riukiu - Taiwan, Manila subduction zone, Sulu Sea, Celebes Sea, Ban Da Sea, North East Sea, Palawan and West East Sea. Of which, the Manila subduction zone (Manila Deep Trough) is considered to have the highest risk.

Earthquake source areas that cause tsunamis can affect Vietnam's coastal and island areas.

An earthquake measuring 8.2 on the Richter scale (Figure 9) occurred in this area on May 26, 2006. Fortunately, this earthquake did not cause a tsunami.

According to scenarios calculated by the Ministry of Natural Resources and Environment, if an earthquake measuring 8.3 on the Richter scale occurs in the Manila Trench, it could create a tsunami 5.2 meters high in Quang Ngai and 2.1 meters high in Nha Trang.

The location of the strongest earthquake recorded on the Manila Trench megafault is illustrated on the map (arrowhead location).

An earthquake measuring 9.2 on the Richter scale in the same area could generate a tsunami 10.6 meters high in Quang Ngai and 5 meters in Nha Trang, and it would take about 2 hours for the tsunami to travel from the Manila Trench to the coast of Vietnam.

Tsunami propagation time from the Manila subduction zone to the coast of Vietnam

Scientifically, earthquakes with a magnitude greater than 6.5 on the Richter scale in coastal areas can cause tsunamis. Therefore, the risk of tsunamis in Vietnam's coastal areas is real and needs attention.