Head of the institute Nguyen Xuan Anh said that this quake was an aftershock of a 5.3-magnitude earthquake that rocked Moc Chau at mid-noon on July 27.
Dozens of aftershocks of this earthquake have occurred with magnitude ranging from 2.6 to 4.0.
Son La is vulnerable to earthquakes as it is located on the Song Da Fault Zone with relatively strong geological activities.
Local authorities are advised to consolidate weak infrastructure, provide people with response skills, and actively evacuate those in risky areas./.VNA
Son La records 20 earthquakes over six-day period
An earthquake measuring 3.6 on the Richter scale rocked Moc Chau district in the northern mountainous province of Son La at 5.31am on August 1, according to data collected by the Institute of Geophysics.