A magnitude-6.7 earthquake struck southwestern Hokkaido early on Sept. 6, causing dozens of casualties, destroying buildings, triggering landslides that buried houses, and cutting off electricity to all homes on the main northern island. Two fatalities were confirmed, in Mukawa and Shin-Hidaka, according to Hokkaido government officials.
And around 30 residents were missing in Atsuma, where the intensity of the quake is estimated to have been an upper 6 on the Japanese seismic intensity scale of 7. Houses in the town were hit by landslides, and one report said five residents were found with no vital signs. Atsuma government officials said at least nine residents might be buried in their homes.
Hokkaido the previous day was hit by Typhoon No. 21, and the heavy rainfall loosened soil on hills and mountains. The quake hit at 3:08 a.m., with the epicenter in the eastern Iburi district that stretches along the southwestern coast. Japan Meteorological Agency (JMA) officials said it was the largest quake to strike the district since records were first taken in 1923. They warned that strong aftershocks could continue for a week.
Another man, 82, in Tomakomai was showing no vital signs after he fell down stairs at his home. One person was listed in serious condition, and nine others suffered slight injuries. An additional 94 people were reportedly injured in the quake, but the extent of their injuries was not immediately known.
The earthquake also caused a chain reaction that led to a power outage at all 2.95 million households in Hokkaido, officials of Hokkaido Electric Power Co. said. The utility explained that a coal-fired thermal plant in Atsuma, the largest in Hokkaido, was heavily damaged in the earthquake. The suspension of operations there caused an imbalance in the supply and demand for electricity. As a result, operations were stopped at all other thermal plants in Hokkaido.
Hokkaido Electric Power officials said they had no idea when operations would resume but were working to start up a hydroelectric plant to resume supplying electricity. The power outage was the first to affect the entire island. Hiroshige Seko, the industry minister, said he expected it would take at least a week before electricity could be restored to all of Hokkaido.
Officials of Hokkaido Electric Power and the Nuclear Regulation Authority said the quake also severed all outside power sources to the Tomari nuclear power plant in Tomari, Hokkaido. But all three reactors were not operating at the time. Six emergency diesel generators were being used to cool spent nuclear fuel stored in a pool at the plant. Officials said the plant had enough fuel to operate the diesel generator for at least seven days.
Officials said no other problems were found at the Tomari nuclear plant, and radiation levels were normal. Transportations systems were in turmoil following the earthquake. Hokkaido Railway Co. suspended operations on all lines from the scheduled start of runs on the morning of Sept. 6. The railway company had no idea when operations would resume.
The subway and streetcar systems in Sapporo, Hokkaido’s capital, were also suspended because of the power outage. The lack of electricity affected New Chitose Airport, which suffered damage to check-in counters and flooding in the passenger terminal building. The airport operator said all flights to and from New Chitose Airport had been canceled for Sept. 6.
According to officials of various fire-fighting units, a large number of homes collapsed in the earthquake. Seventeen homes were reported damaged in Atsuma, three in Abira, two in Mukawa and one in Tomakomai. Soil liquefaction also damaged roads, making many of them unpassable. Employees of the local office of the JMA were heading to the Atsuma area to locate seismic meters that failed to transmit the quake’s intensity in its immediate aftermath.
The lack of data meant JMA officials were not sure of the exact strength of the quake in parts of the area hardest hit in the disaster. The quake also apparently sparked a fire at a steel plant in Muroran within the grounds of the Muroran Works of Nippon Steel & Sumitomo Metal Corp. However, the fire was nearly extinguished by 6:10 a.m. and no injuries or major damage were reported at the plant.