The mysterious cracks in the ground, discovered in Di Linh Town, in the Central Highlands province of Lam Dong, are likely caused by active fault lines, but are no cause for concern of a possible earthquake, seismic experts have said.

Residents on Nguyen Van Troi Street were told to evacuate after the cracks pulled down a house last Sunday, putting at least 20 houses at risk by damaging their walls.

The speed at which cracks have been widening, first noticed by locals about a week ago, finally slowed down during the last two days, the provincial Natural Resources and Environment Department Deputy Director Luong Van Ngu told Viet Nam News yesterday.

The cracks are currently 2m deep and between 10-15cm wide, covering an area of 15ha.

While Ngu said tests conducted last Wednesday showed that the cracks might be the result of the over-exploitation of underground water supplies, Ha Noi-based associate professor Cao Dinh Trieu denied the possibility.

“The exploitation of underground water supplies could have caused the appearance of cracks if this was a low lying delta region, but they are in the highlands,” said Geophysics Institute expert Trieu, who is second vice president of the Asian Seismological Committee.

“It is likely that there has been movement in underground faults [a planar fracture or discontinuity in the volume of rock, across which there has been significant displacement] but no earthquake or tremor could result because of this,” he said.

Dr Do Van Linh, deputy head of the Southern Geological Map Federation, agreed, saying that the cracks involve a fault line named Bao Lam – Tam Hiep, which has seen recent activities.

“If cracks in rock and soil occur underground, there can be no earthquakes seeing as fault energy has already been released,” said Linh.

This view is shared by associate professor Nguyen Dinh Hoe from the Viet Nam Association for the Conservation of Nature and the Environment.

However, deputy chairman of the Viet Nam Geophysics Association Truong Minh suggested that more on-site research be conducted.

In the mean time, Ngu said provincial officials were “doing their best to ensure the safety of inhabitants and their properties.”

Trieu did warn that the cracks would become much worse after it rains.

Linh added that petrol and chemical containers as well as nearby dams should be put under strict supervision to prevent any leakage.

Cracks of smaller sizes are not uncommon in mountainous areas of Viet Nam, according to scientists.

Source: VNS