The weather agency on Monday ended a weeklong advisory for an increased risk of a strong earthquake after a magnitude 7.7 temblor struck off the Pacific coast in northeastern Japan, although it called for continued daily preparation against disasters.
Early in the morning, an earthquake with a preliminary magnitude of 6.2 jolted Hokkaido in northern Japan. The Japan Meteorological Agency said it believes the two quakes were not directly related and that it would not issue a new advisory.
The quake advisory affecting seven prefectures from Hokkaido to Chiba was issued a few hours after a M7.7 quake rattled Aomori Prefecture and its vicinity at 4:52 p.m. on April 20., also triggering tsunami as high as 80 centimeters that reached Kuji Port in Iwate Prefecture.
It was the second time since December that such an alert had been issued, warning of a relatively higher possibility that large earthquakes may occur in areas along the Japan and Chishima trenches, which run along the Pacific coast of northeastern Japan and Hokkaido.
The advisory calls for “special” readiness, such as being ready to evacuate immediately whenever a tremor is felt or a tsunami warning is issued, while continuing socioeconomic activities. It was in place until 5 p.m. Monday.
The total number of injuries in Hokkaido, Aomori and Iwate prefectures reached 10, according to the Fire and Disaster Management Agency. More than 100 schools in the three prefectures were temporarily closed, according to a tally by the Ministry of Education, Culture, Sports, Science and Technology.
The latest quake at 5:23 a.m. Monday struck the Tokachi region of the northern main island, registering upper 5 on the Japanese seismic intensity scale of 7 in the town of Urahoro. The focus of the quake was located at a depth of 83 kilometers.
A woman in her 90s living in a facility in Hakodate was slightly injured when she fell, according to police. The Hokkaido Shinkansen bullet train service was not disrupted by the quake, according to operator JR Hokkaido.
The quake advisory system, officially called the “Off the Coast of Hokkaido and Sanriku Subsequent Earthquake Advisory,” is based on lessons learned from the M9.0 megaquake that devastated northeastern Japan on March 11, 2011, followed by an M7.3 temblor.
The country estimates that up to 199,000 people could die in the event a worst-case quake occurred along the Japan and Chishima trenches, with tsunami waves reaching nearly 30 meters in some areas. However, it also said fatalities could be reduced by 80 percent through enhanced evacuation measures.
© KYODO
