An earthquake measuring upper-5 on the Japanese seismic intensity scale of 7 shook Aomori Prefecture and other parts of the north on Tuesday afternoon, hours after another temblor triggered a small tsunami.
The second instance did not result in a tsunami alert.
The quake struck at 1:46 p.m. The Japan Meteorological Agency described it as magnitude 5.7, with an epicenter around 50 km off the coast of Iwate Prefecture and 50 km deep.
One of the hardest-hit districts was the town of Hashikami, where upper-5 was recorded. It registered as 5-weak in the village of Fudai in Iwate Prefecture.
There were no reported problems at nuclear plants in the area, Kyodo reported.
Earlier in the day, a small tsunami struck the coast of Iwate Prefecture, with a maximum surge of 20 cm recorded at one location.
The tsunami was triggered by a subsea quake with an estimated magnitude of 6.9. It struck on Tuesday morning about 210 km east of the city of Miyako and 10 km deep, the agency said.
Sirens sounded as residents sought higher ground. The largest tsunami waves were measured between 8:35 a.m. and 9:07 a.m. at a port in the city of Kuji, and a 10-cm surge was recorded in Miyako. A smaller tsunami reached the city of Kamaishi, the agency said.
Evacuation orders were issued for residents in coastal districts of Kuji and the town of Otsuchi, and evacuation advisories for the cities of Ofunato and Rikuzentakata as well as Kamaishi.
The Iwate Prefectural Government reported no damage from the waves.
The quake hit at 8:06 a.m. It measured 4 on the Japanese seismic intensity scale of 7 in Iwate and three other prefectures in Tohoku — Aomori, Akita and Miyagi.
The quake was believed to be an aftershock of the 9.0-magnitude earthquake that hit the Tohoku region on March 11, 2011, the meteorological agency said.
Tohoku Electric Power Co., which operates the Onagawa and Higashidori nuclear plants in nearby Miyagi and Aomori prefectures, said it saw no irregularities at the facilities after the quake.
All 48 of Japan’s workable nuclear reactors remain offline after the March 2011 earthquake and tsunami triggered the Fukushima No. 1 plant meltdown disaster.
A spokesman for Tokyo Electric Power Co., the operator of Fukushima No. 1 and Fukushima No. 2 nuclear plants, said there were no irregularities at the plants. The quake was felt only weakly in the area, he said.
Unlisted Japan Nuclear Fuel Ltd. also said there were no irregularities recorded at its nuclear fuel reprocessing facility or other plants in Aomori.
East Japan Railway Co. briefly halted Tohoku Shinkansen bullet trains between Furukawa Station in Miyagi and Shin-Aomori Station in Aomori amid a power failure.
The evacuation instructions and advisories were lifted at 10:20 a.m.
Large areas of the coastline covered by Tuesday’s warning were damaged by the 2011 quake and tsunami that killed more than 18,000 people and triggered a nuclear disaster.
Earthquakes are common in Japan, one of the world’s most seismically active areas. The nation accounts for about 20 percent of the world’s earthquakes of magnitude 6 or greater.