A powerful 7.5-magnitude earthquake struck northeastern Japan on Monday night, prompting evacuation orders for about 90,000 residents and tsunami warnings that hours later were downgraded to warnings.
The Japan Meteorological Agency (JMA) had initially said that a tsunami up to 3 meters high could hit the northeast coast of Japan after the earthquake struck at 11:15 pm (11:15 am Brasília time) off the coast.
Tsunami warnings were issued for Hokkaido, Aomori and Iwate prefectures, and tsunamis 20 to 70 cm high were observed at several ports, the JMA said.
Continues after advertising
Early Tuesday morning local time, the JMA downgraded the alerts to warnings, meaning there is now an estimated lower wave height and less risk of flooding.
The earthquake’s epicenter was 80km off the coast of Aomori Prefecture, at a depth of 54km, the agency added.
On the Japanese seismic intensity scale that goes from 1 to 7, the tremor was registered as “upper 6” in the city of Hachinohe, in Aomori Prefecture — strong enough to make it impossible to stand or move without crawling. In such tremors, most heavy furniture can collapse and wall tiles and window panes are damaged in many buildings.
As of 2pm (Brasília time), there was little information from public broadcaster NHK about major damage or casualties. The broadcaster quoted an employee at a hotel in Hachinohe as saying that injured people were taken to hospital, but all were conscious.
“So far, I am aware that there have been seven injuries,” Prime Minister Sanae Takaichi told reporters on Tuesday morning (local time).
East Japan Railway suspended some services in the area, which was also hit by the powerful 9.0 magnitude earthquake in March 2011.
Continues after advertising
“There is a possibility that more strong and powerful earthquakes will occur in the coming days,” a JMA official said at a meeting.
Following the quake, the JMA issued a warning for a wide region from the northernmost island of Hokkaido to Chiba prefecture, east of Tokyo, asking residents to be on alert for the possibility of a strong earthquake within a week.
No irregularities were reported at the region’s nuclear plants run by Tohoku Electric Power and Hokkaido Electric Power, the utility companies said. Tohoku Electric initially said thousands of homes had lost power, but later reduced that number to hundreds.
Continues after advertising
Japan is one of the most earthquake-prone countries in the world, with a tremor occurring at least every five minutes. Located on the “Ring of Fire” of volcanoes and ocean trenches that partially surround the Pacific Basin, Japan is responsible for about 20% of earthquakes of magnitude 6.0 or greater.
The northeast region suffered one of the country’s deadliest earthquakes on March 11, 2011, when a magnitude 9.0 tremor struck the ocean off the coast of the northern city of Sendai. It was the most powerful ever recorded in Japan and triggered a series of massive tsunamis that devastated a large swath of the Pacific coast and killed nearly 20,000 people.
The 2011 tsunami also damaged the Fukushima Daiichi nuclear plant, leading to a series of explosions and meltdowns in the world’s worst nuclear disaster in 25 years.
Continues after advertising
Building on lessons from that disaster, when a magnitude 7 earthquake occurred two days earlier, the government now issues a one-week “mega earthquake” warning whenever a significant earthquake occurs in the region. Similarly, in August last year, a mega earthquake warning was issued for the Nankai Trough area in south-central Japan.
