- 2016-04-15 16:25:06 (UTC)
- 2016-04-15 18:25:06 (UTC+02:00) in your timezone
- Times in other timezones
- 1.0 km (0.6 mi) WSW of Kumamoto-shi, Japan
- 12.0 km (7.5 mi) NNE of Uto, Japan
- 13.0 km (8.1 mi) SSE of Ueki, Japan
- 15.0 km (9.3 mi) NNE of Matsubase, Japan
- 631.0 km (392.1 mi) SSE of Seoul, South Korea
The April 15, 2016 M 7.0 earthquake north of Kumamoto, on the island of Kyushu in southwest Japan, occurred as the result of strike-slip faulting at shallow depth. Focal mechanisms for the earthquake indicate slip occurred on either a left-lateral fault striking to the northwest, or on a right-lateral fault striking northeast. While the earthquake occurred several hundred kilometers northwest of the Ryukyu Trench, where the Philippine Sea plate begins its northwestward subduction beneath Japan and the Eurasia plate, the shallow depth and faulting mechanism of this earthquake indicate it occurred on a crustal fault within the upper Eurasia plate. At the location of this event, the Philippine Sea plate converges with Eurasia towards the northwest at a velocity of 58 mm/yr.
The April 15, 2016, M 7.0 event (UTC 16:25:06) occurred one day after a series of foreshocks in the same region, which included M 6.2 and M 6.0 earthquakes. The April 14 events resulted in at least 9 fatalities and over 800 injuries.
In contrast to this recent sequence of shallow earthquakes, most seismicity in the Kyushu region is related to the subduction of the Philippine Sea plate at depth. Just thirteen M 5+ earthquakes have occurred at shallow depths (< 50 km) within 100 km of the April 2016 events over the preceding century. In January and April of 1975, two shallow events with magnitudes of M 5.8 and M 6.1 - 40 km and 65 km to the northwest of the April 2016 earthquake, respectively – caused injuries, but no known fatalities. A shallow M 6.6 earthquake in March 2005, just off the north coast of Kyushu and 110 km north of the April 2016 event, caused over 1000 injuries and at least one fatality.
Mapped faults in the region generally trend east-west or northeast-southwest, in agreement with the right-lateral plane of preliminary focal mechanisms, and the trend of early aftershocks. Since the April 14, M 6.2 event (12:26:36 UTC), 19 other shocks have been located, including the latest M 7.0 earthquake.