At 8pm Vietnam time, CNN, BBC, AP and others carried news of the tsunami off the southern Taiwanese coast. It later killed one and injured three in the Chinese territory.
Vietnam, which as yet has no equipment to predict tsunamis, immediately stirred into action.
Vietnam's National Hydrometeorology Center and the Steering Committee on Flood and Storm Prevention instructed provinces stretching from Quang Binh to southernmost Ca Mau in the central and southern region to move residents at coastal areas deeper inland, and call vessels ashore.
Around 2 hours after the first warning, the Japanese said the tsunami was unlikely to pose a threat and one hour later at 11pm, Vietnam reported the danger over.
But in that short span of time, the Vietnamese government managed to put one half of the nation on full alert, with thousands ready to be evacuated any time.
Mass preparation
Deputy first Prime Minister Nguyen Sinh Hung immediately arrived at the central weather bureau to hear updates on the seaquake.
At 10.30pm, central Quang Binh province mobilized all soldiers ready to evacuate over 10,000 locals.
In former imperial Hue city, over 15,000 started their evacuation.
In Da Nang, plans to move 20,000 residents to safety were in place.
Deputy PM Hung said after the incident, “This was an important drill for real calamities”. He instructed provinces to return to normalcy but to be on guard against possible aftershocks.
He also instructed weather agencies to keep a close watch on international forecasts and warnings.
The country has 24 stations to monitor earthquakes but none to predict tsunamis.
This Thursday, the Vietnamese Institute of Geophysics will hold a conference to discuss earthquakes and tsunamis.
The Japan Meteorological Agency reported the seaquake as occurring at 19:34pm Vietnam time (1234 GMT).
According to China Seismological Bureau, two quakes - the first measuring 7.2 on the Richter scale and the second measuring 6.7 - hit the East Sea.
The epicenter was located at 21.9 degrees north latitude and 120.6 degrees east longitude, about 350 kilometers from the Chinese mainland and 15 kilometers from Taiwan.
Labels: Vietnam