vietnam earthquake july 2014 map
Muong La District (in the red dashed line) in the northern Vietnamese province of Son La is seen in this Google Map screen capture.
The northern Vietnamese province of Son La experienced three earthquakes in a row on Saturday night, one of which reached a magnitude of 4.3 on the Richter scale, the Earthquake Information and Tsunami Warning Center said.

The three quakes struck Muong La District and their aftershocks were felt in Hanoi, 278 km away from Son La, according to the center under the Institute of Global Physics.

The first quake measuring magnitude 4.3 rocked the district at 7:14 pm, with its epicenter around eight kilometers underground.

The tremor lasted for about 30 seconds, shaking or throwing household furniture and tools to the ground, local residents said.

Many people rushed out of their houses during the earthquake, locals said.

Another quake happened in the same district at 8:20 pm, with a lower strength of magnitude 3.2. Its epicenter was the same as that of the previous one.

More than an hour later, the third earthquake, measuring magnitude 3.5, hit the locality at 9:42 pm, with its epicenter about seven kilometers underground.

Many local residents, especially those who live in multi-storey houses, said they clearly felt the shakes caused by the three quakes, particularly the first one.

Nguyen Hong Phuong, director of the Earthquake Information and Tsunami Warning Center, said the three quakes occurred within the active Muong La-Bac Yen fault, which can trigger shakes at any time.

Nguyen Van Tam, head of the Muong La District Agricultural Department, said local authorities have yet to receive immediate reports on the damage brought about by the quakes.

This was not the first time that Son La had experienced such quakes, the center said.

Earlier this year, a quake measuring magnitude 2.6 shook the province at 12:55 pm on January 11, with its epicenter located roughly nine kilometers underground.

On August 6 last year, a magnitude-2.1 quake occurred in an area near the Son La Hydropower Plant in Muong La District.

Another much stronger tremor, measuring magnitude 4.1, hit Bac Yen District, 37 km southeast of the plant, at noon on November 26, 2009. On the evening of the same day, another magnitude-4.2 quake struck the same area, the center said.