Japan could face another mega earthquake, according to researchers in Japan, who have detected and traced shallow tremors under the ocean floor. It is the first time this technique has been used to predict earthquakes. Japan is located in the most powerful seismic network in the world — having dealt with a devastating magnitude-9.0 earthquake as recently as 2011, which claimed the lives of near 16,000 people. The earthquake caused a tsunami along with a nuclear disaster in Fukushima. The World Bank estimated that the tsunami and earthquake that rocked Japan in March of 2011 was the most costly natural disaster in world history, at $235 billion.

In a subduction zone, one plate slides beneath another into the mantle, the hotter layer beneath the crust. The great plates are rough and stick together, building up energy that is released as earthquakes. East of Japan, the Pacific plate dives beneath the overriding Eurasian plate. The temblor completely released centuries of built up stress between the two tectonic plates, a recent study found. According to reports, the researchers in Japan used Ocean Bottom Seismometers to measure motion under the sea. This technique is used to detect low-energy, slow earthquakes along the trenches that we otherwise would not notice. MORE