HANOI - Two earthquakes happened early Friday morning in Vietnam's northern province of Son La, and they have caused no damages or casualties so far, Vietnam News Agency reported.

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An expert from the Vietnam Academy of Science and Technology said that the reason was the earthquakes occurred in the mountainous areas with few inhabitants.The first earthquake happened with magnitude of 5.5 Richter scale. The second earthquake happened a few hours after the first one measuring 4.0 Richter scale.

It is believed to be the aftershock of the first earthquake, said Vietnam News Agency.

Vietnamese scientists on geophysics are keeping their eyes on these earthquakes, said the report.