April 15: A magnitude 7.4 earthquake struck southern Japan early on Saturday morning, triggering a tsunami advisory. The quake's epicentre was near the city of Kumamoto and measured at a depth of 40 km (25 miles), the US Geological Survey said. The USGS minutes earlier reported a 7.1 quake with a depth of 7 km close to the same location. The Japan Meteorological Agency issued a tsunami advisory, which identifies the presence of a marine threat and asks people to leave coastal regions, for the Ariake and Yatsushiro seas. Local broadcaster NHK said the advisory suggested a possible wave of one metre in height. Magnitude 7.4 earthquake hits near Japan's Kumamoto: USGS April 15:  A magnitude 7.4 earthquake struck near Kumamoto in southern Japan on Friday at a depth of 40 km (25 miles), the US Geological Survey said. It earlier reported a 7.1 quake with a depth of 7 km close to the same location.