Red River Fault Zone Causes Earthquake in Hanoi

The earthquake in My Duc district that caused inner Hanoi to shake on the morning of March 25 was due to the activity of the Red River fault zone, according to experts from the Institute of Geophysics.

According to the Earthquake Information and Tsunami Warning Center (Institute of Geophysics), at 8:05 a.m. in My Duc district, a 4.0 magnitude earthquake occurred at a depth of about 16 km, causing many people in Hanoi's inner city to feel the shaking for 3-5 seconds. The disaster risk level is 0.

Sharing with VnExpress, Associate Professor Dr. Nguyen Hong Phuong, a seismologist at the Institute of Geophysics, initially determined that the cause was a tectonic earthquake, caused by a natural fault zone (a geological phenomenon related to tectonic processes in the Earth's crust. Usually, faults often occur in places with unstable geological conditions).

According to Associate Professor Phuong, the earthquake in My Duc occurred because it was only about 1.8 km away from the Red River fault zone - the source of the earthquake, running through the boundary of Hanoi City. This is a fault that stretches over 1,000 km, originating from Yunnan (China) down to Northern Vietnam, extending to Vinh Phuc .

This fault is in a dormant period and this era lasts for several thousand years, according to experts' forecasts. Therefore, along this fault zone, only medium or small earthquakes arise.

In Vietnam, to date, only about 30 small earthquakes with magnitudes of about 3 to 4 have been recorded. "According to the moment magnitude scale, these earthquakes do not exceed 6 degrees, so they do not cause house collapse or human damage," Mr. Phuong emphasized.

The earthquake occurred in My Duc district, about 50 km from the center of Hanoi. Graphics: Hoang Khanh — The earthquake occurred in My Duc district, about 50 km from the center of Hanoi. Graphics: *Hoang Khanh*

Associate Professor Phuong added that the earthquake in My Duc is different from the type of induced earthquake that occurred in Kon Plong district, Kon Tum province. The induced earthquake is caused by human impact on the environment, specifically occurring in a hydroelectric area with a reservoir that compresses the layer causing the induced earthquake. Meanwhile, the earthquake in Hanoi occurred on the Red River fault zone, caused by nature causing deep cracks on the Earth's surface, which are considered "throats for releasing energy from underground, manifesting as earthquakes, called tectonic earthquakes".

Because it was not very active, the tectonic earthquake in My Duc did not pose any danger. However, he advised people to be vigilant. The Institute of Geophysics is currently monitoring aftershocks after the earthquake.

Dr. Nguyen Xuan Anh, Director of the Institute of Geophysics, explained the earthquake laws caused by seismic faults in the Red River - Lo River - Chay River fault zone, showing that a strong earthquake usually occurs every hundred years, or five or seven hundred years. It is necessary to study the Red River fault segment to assess earthquake hazards in more detail, and the Hanoi area needs to conduct an earthquake risk assessment.

He also proposed setting up some monitoring equipment in high-rise buildings in the city to quantitatively assess the level of shaking caused by earthquakes.

Experts say it is very difficult to predict exactly when an earthquake will occur, even in Japan, scientists do not know if it will happen tomorrow. However, scientists can predict the magnitude of the earthquake in that area, or how high it will reach. "Therefore, people need to follow official information to respond promptly," Associate Professor Phuong said.

Nhu Quynh

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