A number of earthquakes in the northwestern region over the last few days has proved the seismic fractures in Vietnam are becoming more active, according to scientists.
A 4.1 magnitude earthquake hit the northwestern province of Lai Chau on Thursday morning, the third quake in the province over the last four days.
The quake lasted several seconds and did not cause any human or material damages.
Previously, two earthquakes measuring 3.8 and 3.6 on the Richter scale shook the province on April 25 and 26.
Le Huy Minh, director of the Center for Earthquake Information and Tsunami Forecasts under the Vietnam Institute of Geophysics, said the three quakes were rather weak and unable to cause damages.
The three quakes brought the number of earthquakes occurring in the Son La and Lai Chau-Dien Bien fracture zones (in the northwestern region) over the last four days to 10.
"However, the other seven quakes measured below 3.5 on the Richter scale, so we did not release earthquake reports," Minh explained.
According to Dr. Minh, the Son La fracture zone may cause a 7 magnitude earthquake, while the maximum magnitude for an earthquake in the Lai Chau-Dien Bien fracture zone is 6.1-6.5.
The consecutive quakes in the provinces over the last 10 days have warned us of more earthquakes in the coming time, he said.
RECENT MAJOR EARTHQUAKES
- A 4.5 magnitude quake in Lai Chau Province in March 2008
- A 5.3 magnitude quake in Dien Bien-Lai Chau in February 2001 leaving four injured and more than 3,200 buildings damaged
- A 6.8 magnitude quake in Dien Bien in 1983
- A 6.7 magnitude quake in Dien Bien Province in 1935
Minh also noted that more and more earthquakes had been happening in other provinces across the country since late last year, compared to previous years.
It seems the seismic fractures in Vietnam are becoming more active, he said.
"It is calculated that an earthquake measuring more than 6 on the Richter scale hits Vietnam every 20-30 years. It is now 28 years since the 6.8 magnitude quake occurred in Dien Bien Province in 1983," said Minh.
"I think the earthquake cycle is back!"
Dao Ngoc Huong, director of Lai Chau Province Department of Agriculture and Rural Development, said the province had yet to receive any official warnings or instructions from state authorities to cope with earthquakes.
"We heard a lot on the radio and TV about earthquake risks in Lai Chau, but no prevention measures have been taken.
"No geologists from any central agencies ever told us how to build earthquake-proof buildings or if it is neccisary."
According to scientists from the Institute of Geophysics, earthquakes in Vietnam are rather weak or moderate compared with the quakes in other countries of the world.
On average, a quake registered 7 on the Richter scale happens every 10 years and a 6 magnitude quake happens every 5 years.
Hanoi is listed in the group with the risk of having earthquake measuring 7-8 while Ho Chi Minh City in the group of 6-7 magnitude.