Japanese ‘mainshock’ causes significant additional damage; semiconductor sector hard hit
The M7.0 earthquake that hit Kyushu, the most south westerly of Japan’s four main islands, last Friday is now being regarded as the main earthquake in a series of events last week with predictions it will cause significant additional damage.
Some 42 people have been killed and more than 1,000 people injured. There has been widespread damage to buildings, houses, roads and bridges. Japan's meteorological agency has also warned that more tremors are likely to hit in the coming days.
AIR Worldwide said the event on Friday will now be regarded as the so-called mainshock with the other events now considered additional foreshocks rather than aftershocks.
According to AIR, 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 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.
As authorities were beginning to assess damage to the building stock, the M7.0 mainshock struck at a similarly shallow depth of 11 km but 15.8 times stronger in its energy release than the previous M6.2 quake, according to the United States Geological Survey (USGS).
Power was cut in many areas, and gas supplies were turned off by Saibu Gas after gas leaks were reported, according to catastrophe modelling firm AIR Worldwide. 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.
According to AIR, Kumamoto Prefecture, in the heart of Kyushu Island, is home to roughly 25 percent 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. 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.
