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Mw 6.2 Earthquake Strikes Japan

16 Apr 2016

On 14 April 2016, the United States Geological Survey (USGS) reported that a magnitude-6.2 earthquake occurred at (32.849°N 130.635°E), north of Kumamoto on the island of Kyushu in southwest Japan. The Japan Meteorological Agency (JMA) estimated the earthquake’s mainshock magnitude to be 6.5, with severe ground-shaking (JMA seismic intensity scale = 7) close to the epicentre.

Dr Wang Yu, a Research Fellow from the Earth Observatory of Singapore (EOS), had observed that the locations of the earthquake’s mainshock (Mw 6.2) and aftershock (Mw 6.0) strongly correlated to the 14-km-long Mifune fault that belongs to the Futagawa-Hinagu fault system – the western extension of the Median Tectonic Line that cuts across from central Honshu to western Kyushu. The current analysis of the earthquake data suggests that the Futagawa-Hinagu fault system is the source of the Kumamoto earthquake.

“From overlaying the earthquake’s epicentres and their fault-plane solutions (the early data on a fault’s orientation and slip) with a map of active faults in Japan, their alignment is very clear,” he explained.

According to EOS geologist Assistant Professor Judith Hubbard, “Although this earthquake was smaller in magnitude than the one underneath Myanmar yesterday, it is likely that this event would result in significantly more damage due to the shallow nature of the earthquake and the greater density of Japan’s population and infrastructure.”

 The aftershocks recorded in the first day after the earthquake are numerous and fall along a trend that is consistent with the known active fault in the region.

 The locations of the earthquake's mainshock and aftershocks show a strong correlation to the Mifune fault.

 

Cover image: US Geological Survey