Ho Chi Minh City has an earthquake map

After four years of research, the Southern Geological Mapping Division has completed a map of earthquakes and influences on Ho Chi Minh City . As expected, Ho Chi Minh City is less prone to earthquakes, but if dynamic Land happens, the level of damage will be very high.

The topic 'Ho Chi Minh City's Small Earthquake Division' was carried out by the Southern Geological Mapping Federation (LDC) within four years (2006-2010), owned by Master Cat Nguyen Hung, Head of the Federation. topic.

Less risk of earthquakes

Before this map was established, history has recorded the aftershocks and earthquakes occurring in the Southeast region. According to the Institute of Geophysics, at 22h18 on August 8, 1964, about 40 km from Can Gio estuary, a 4.8-degree Ritchter earthquake occurred, at a depth of 15 km. This is considered the most recent earthquake recorded in Ho Chi Minh City area.

Then, at 719 on October 26, 1964, there was also an earthquake of 2.7 Ritchter magnitude at a depth of 15 km, in the area of ​​Loc Ninh - Binh Long (Binh Phuoc). Most recently, on August 26, 2002, an earthquake with a magnitude of 3.9 on the Richter scale occurred and caused a severe tremor at level 5 in Ward 10, Vung Tau City and Long Hai.

Through these earthquakes, many scientists have pointed out that the cycle of activities in the South Central Coast and South Vietnam is about 40 years. In particular, HCMC is identified as the least affected area in the Southeast.

The faults in the earth in the West Sea, Cuu Long - Con Son, Thuan Hai - Minh Hai, Hau River . have been associated with volcanic activity, earthquake source area. However, in this study, scientists at the DMU have pointed out that the fault zone that can occur earthquakes near HCMC is Saigon River and Vam Co Dong River. However, this fault is very unlikely to happen.

Geological structure map.The darker areas of the earthquake effect will be less, the light area will affect more.

In the event of an earthquake, scientists predict that the strongest earthquake intensity will not pass 5.5 degrees Ritchter and the seismic depth does not exceed 17 km. In particular, the scientists, after performing gravity measurements at 10,000 points in the Ho Chi Minh City area, have established a tectonic map of geological structure; identify sources of earthquakes and influences on HCMC; established a ground vibration map for the city when an earthquake hit. These are indispensable elements in planning and construction of works in the city.

Large damage easily due to weak soil

Despite being identified as a low-risk area, the level of damage is determined to be high, level 7/12, if an earthquake occurs in HCMC. The main reason is due to the weak soil structure in Ho Chi Minh City, leading to great damage to the construction works. At the same time, the density of population concentration, infrastructure, production . will lead to serious devastation levels.

However, in the short term, according to Dr. Huynh Ngoc Sang, Ho Chi Minh City National University, the risk of liquefied soil in HCM City is considered very high, even when there is no earthquake. In Ho Chi Minh City, many buildings and properties have been recorded in the ground to tens of meters, such as the sinking of 1,200 tons of billet steel, up to 23 meters deep, at a steel warehouse in Binh Dien (Binh Chanh district). in 2000 ; the sinking of 1,000 tons of steel sheet, 20 meters deep, in ward 25, Binh Thanh district in 2002 . The phenomenon of subsidence of load blocks in construction works is not too rare. Geological structure in the riverside area and the South of Saigon (District 7, Binh Chanh, Can Gio) is very popular with this liquefied soil phenomenon.

'This is an issue to consider in construction projects', said Dr. Huynh Ngoc Sang. According to Associate Professor Dr Cao Dinh Trieu, Vice Chairman of the European Geological Society, this phenomenon is due to the fact that this area is young, weak and not well connected.

The above research work has been highly appreciated by the scientific council, it is necessary to soon apply the construction standards in the planning of HCMC.