TOKYO–A powerful earthquake struck off the northern Japanese coast earlier Monday, and the Japan Meteorological Agency issued a tsunami alert in the region, sending residents to rush over to safer grounds.
Two hours after the tremor, which struck at 4:52 p.m. local time, tsunami waves as high as 2.6 feet had been detected, though warnings remained for possible bigger waves at the top of Japan's main Honshu island, and the northern Hokkaido region. A smaller tsunami of 1.3 feet was recorded at another port in the prefecture, the agency said.
There were no immediate reports of casualties or major damage, Japan's top government spokesperson Minoru Kihara told a news conference as night fell in the capital Tokyo.
Several port towns, including Otsuchi and Kamaishi–both hard-hit by a massive earthquake and tsunami in 2011– earlier issued evacuation orders for thousands of residents, according to public broadcaster NHK. Bullet train services were halted and some motorways were closed due to the tremors.
No Abnormalities Reported at Idled Nuclear Plants
The quake measured an 'upper 5' on Japan's seismic intensity scale–strong enough to make it difficult for people to move around and cause unreinforced concrete-block walls to collapse. The tremor had an epicentre in the Pacific Ocean and was 10 km deep, JMA said.A 3-metre tsunami could cause damage to low-lying areas by flooding buildings and carrying off anybody exposed in its currents, according to JMA.
Located in the "Ring of Fire" of volcanoes and oceanic trenches partly encircling the Pacific Basin, Japan is one of the world's most earthquake-prone countries, with a tremor occurring at least every five minutes.
It accounts for about 20 percent of the world's earthquakes of magnitude 6.0 or more, such as the 2011 disaster that caused nuclear meltdowns at a Fukushima power plant.
Advisory Issued for Slightly Increased Risk of Mega-Quake
Japan on Monday issued an advisory for northern coastal areas for an increased risk of a possible mega-quake induced by a major quake earlier in the day.The Cabinet Office and the Japan Meteorological Agency said there is 1 percent chance for a mega-quake occurring on the northern Japanese coast in the next week or so, following the powerful quake earlier Monday near the Chishima trough.
Officials said the advisory is not a quake prediction but urged residents to raise their preparedness, such as emergency food and their grab bag just in case, while continuing their daily lives.
The advisory for the region is the second in recent months. One was issued following another major quake in December. No major subsequent quake occurred.