Scientists trigger artificial quake in Japan

Tokyo: Researchers on Thursday triggered an artificial earthquake on a mountain in Japan in search of data to help find signs of possible volcanic eruptions.

Mount Zao is 1841 metres high and located between Miyagi and Yamagata prefectures. It has become active since the massive earthquake in March 2011, with increased volcanic tremors, public broadcaster NHK reported.

A team from Tohoku University, together with Meteorological Agency officials, conducted a new survey of the volcano in the early hours of Thursday.

They detonated about 200 kg of dynamite inside a 40-metre deep hole dug on the mountain side.

Water poured inside the hole spewed out with the force of the blast.

Seismic waves from the blast were measured by about 150 seismometers placed on the mountain.

Since seismic waves travel more slowly through water, analysis of seismometer data enables researchers to estimate pools and pathways of hot water up to about two km underground.

Tohoku University Professor Satoshi Miura says finding out the locations of hot water is a key to guessing where the next steam-blast explosion could occur.

Mount Zao last erupted in 1940.