mount zao
Tokyo researchers triggered earthquake to search for signs of future volcanic eruptionsChampagneFight/CC

Scientists in Japan have triggered an artificial earthquake on Mount Zao using 200kg of dynamite in order to study signs of future volcanic eruptions. The team from the Tohoku University and Japan Meteorological Agency conducted a new survey of the volcano, which became active following the 2011 earthquake and tsunami.

Mount Zao is on the border between Yamagata Prefecture and Miyagi Prefecture at an elevation of 1,841m. The 2011 Tōhoku earthquake triggered volcanic subsidence in eastern Japan and induced seismic activity in some volcanic regions.

Earlier this year experts issued an alert for a possible eruption at Mount Zao following a large amount of tremors observed in April. The volcano last erupted in 1940. At present, there is no way of predicting when volcanoes might erupt. While increased volcanic tremors are thought to be an indicator, they are very common with active volcanoes and often take place with no ensuing eruption.

Scientists detonated the dynamite inside a 40m deep hole that had been dug on the mountainside, NHK reported. Researchers poured water inside the hole, which was then spewed out with the force of the blast. The researchers measured seismic waves from the blast with 150 seismometers placed on the mountain – seismic waves travel slower through water, allowing researchers to estimate pathways and pools to a depth of around 2km.

Eruptions take place when magma comes into contact with water. It evaporates and causes an explosion inside the volcano. Researcher Satoshi Miura said finding the location of this hot water is important in establishing where the next steam blast explosion might take place.