A powerful earthquake struck northeastern Japan on Tuesday morning, briefly disrupting nuclear fuel cooling functions at the Fukushima No. 2 power plant and generating tsunami of over 1 meter in the region that was devastated by the Great East Japan Earthquake, tsunami and nuclear disaster five years ago.

The 5:59 a.m. quake with a preliminary magnitude of 7.4 is believed to be an aftershock of the March 2011 mega-quake, the Meteorological Agency said.

It was the first quake with a magnitude of 7 or bigger to hit Japan since July 2014. The agency warned that there may be similar-scale quakes for around a week.

A tsunami measuring 1.4 meters high was observed at Sendai port in Miyagi Prefecture and a wave of about 1 meter reached the coast near the Fukushima No. 1 nuclear plant that was crippled by the 2011 quake-tsunami disaster.

Authorities instructed residents in coastal areas to evacuate to higher ground and hundreds of schools canceled classes. Over 3,000 people fled to evacuation centers in Fukushima Prefecture.

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“The sound of sirens brought back memories of the huge earthquake (in 2011),” said Tomomi Nagakubo, 48, who drove her car to an evacuation center in Ibaraki Prefecture with her 13-year-old son.

According to the Fire and Disaster Management Agency, a total of 17 people in Fukushima, Chiba, Tokyo and Miyagi prefectures were injured as a result of the quake. They included an 82-year-old woman in Chiba who fell down some stairs in her home and fractured her hip. In Fukushima, three people were injured, two of whom were elderly women who tripped and suffered broken bones.

The cooling system for the spent fuel pool in the No. 3 reactor building at the Fukushima No. 2 power plant stopped working but was restarted about 100 minutes later, according to operator Tokyo Electric Power Company Holdings Inc.

“I have been informed that it will not immediately lead to a radiation leak or an increase in the temperature of the fuel,” Chief Cabinet Secretary Yoshihide Suga said in a news conference in Tokyo.

Equipment to measure dust for radioactive materials at the Fukushima No. 2 complex also stopped working, but Tepco said the glitch did not cause any serious problems.

No abnormalities were observed at other nuclear plants in northeastern Japan, according to Tepco and other power companies. Reactors at these nuclear plants have been offline.

Sixteen small boats were overturned off the coast of Miyagi Prefecture, the Japan Coast Guard said, adding no one was believed to be onboard.

All tsunami warnings and advisories were lifted as of 12:50 p.m., the Meteorological Agency said.

The quake, which also shook the Tokyo area, measured lower 5 on the Japanese seismic intensity scale of 7 in Fukushima, Ibaraki and Tochigi prefectures, the agency said.

It was the first time since December 2012 that the agency issued a tsunami alert due to an aftershock from the 2011 quake.

Television footage showed ships moving out to sea from harbors as tsunami warnings wailed after alerts of waves of up to 3 meters were issued.

“We saw high waves but nothing that went over the tidal waves,” a man in Iwaki, Fukushima Prefecture, told NTV.

Aerial footage showed tsunami flowing up rivers in some areas, as well as the overturned fishing boats in the port of Higashimatsuyashima, Miyagi Prefecture.

The focus of the quake was about 25 km under the seabed in the Pacific Ocean off Fukushima, the agency said.

Prime Minister Shinzo Abe said in a news conference in Buenos Aires that the government will assess the damage and keep the public informed.

KEYWORDS fukushima, tsunami, earthquakes, disasters