Kumamoto Earthquake

Update 1 | Summary
Posting Date: April 15, 2016, 2:00:00 PM

It has been little more than 24 hours since yesterday’s M6.2 Kyushu earthquake. Even as authorities were beginning to assess damage to the building stock, the M7.0 mainshock struck at 1:25 a.m. JST Saturday April 16 (16:25 UTC Friday April 15), at a similarly shallow depth of 11 km but 15.8 times stronger in its energy release than yesterday’s M6.2 quake, according to USGS. The Japan Meteorological Agency issued tsunami advisories for both the Ariake Sea and Yatsushiro Sea but then lifted them less than an hour later. Seven earthquakes, now considered additional foreshocks rather than aftershocks, occurred within just the first three hours of the initial quake, including one M6.0 event.

ShakeMap for the M7.0 earthquake that struck Kyushu on April 16, 2016 (4:25 UTC). Source: USGS

Reported and Potential Residential Impacts

Given that the mainshock struck in the middle of the night, there is still very little known about the damage this quake has caused. However, damage from the previous quake has become better known. Power was cut in many areas, and gas supplies were turned off by Saibu Gas after gas leaks were reported. Tens of thousands of households were without running water. Before the M7.0 mainshock, many buildings were assessed to have structural damage that may make them uninhabitable and 20 buildings collapsed. Tens of thousands of people have been displaced and are in shelters.

A national treasure and popular tourist attraction in Japan, Kumamoto Castle was heavily damaged. Seven fires were reported. Given the mainshock’s shallow depth and proximity to population centers, it is expected to cause significant additional damage, particularly to Japan's traditional wood frame building stock. The number of fatalities from yesterday’s event has remained at nine and the number of injured has exceeded 1,000 according to some estimates; these numbers will now likely rise, perhaps significantly.

Early video footage of the aftermath of the quake has been released by Japan’s NHK broadcasting company and is available at this link: http://www3.nhk.or.jp/nhkworld/en/news/20160416_04/

Potential Commercial/Industrial Impacts

Kumamoto Prefecture, in the heart of Kyushu Island, is home to roughly 25% of Japan’s semiconductor production, including some of the country’s leading manufacturers. In addition, there are more than 100 semiconductor-related enterprises located in the prefecture. So intertwined is Kyushu with Japan’s semiconductor production, in fact, that Kyushu is referred to informally as “Silicon Island.” The area also has automobile, steel, and ship manufacturers. The quake could cause business interruption losses and further impact supply chains, but that has yet to be seen.

It is still in the very early aftermath of this event. The AIR Earthquake team is analyzing the available ground motion information and will continue to monitor the situation over the course of the weekend. Additional information will be made available early next week.

Update 1 | Downloads
Posting Date: April 15, 2016, 2:00:00 PM