An earthquake expert from Japan's Meteorological Agency, Yasuhiro Yoshida, speaks at a press conference at their headquarters in Tokyo on Feb. 17, 2015 after an earthquake hit northern Japan.
Yasuhiro Yoshida, speaks at a press conference at their headquarters in Tokyo on Feb. 17, 2015

6.7 earthquake jolts northern Japan, triggers tsunami warning

Updated

A shallow 6.7-magnitude earthquake jolted northern Japan early Tuesday, triggering a tsunami warning and advisories cautioning people to stay away from the coast. The warning and advisories ended later Tuesday.

A second earthquake, which registered a magnitude of 5.7, also struck on Tuesday in the area. There are two nuclear power plants in the region of the second quake, but no irregularities were reported at either site, according to Japanese media. There were no concerns of tsunami resulting from the second quake as of press time.

The first quake on Tuesday struck off the coast of Iwate Prefecture, where authorities had issued a tsunami warning and expected 3-feet-high waves. The quake’s epicenter was 50 miles north of Miyako and 330 miles north of Tokyo, at a depth of 14 miles, according to the U.S. Geological Survey.

No damages or injuries were reported.

Onagawa Nuclear Power Plant in Miyagi Prefecture said there haven’t been any disruptions or damage from the quake and bullet trains were running on regular schedules, Japan’s NHK television reported.

Japan’s Meteorological Agency cast the quake as an aftershock of the 9.0 temblor that rocked Japan on March 11, 2011, killing at least 15,800 people and caused the meltdown of three reactors at the Fukushima Daiichi Nuclear Power Plant.

“Because the 3/11 earthquake had such a strong impact, and because it’s an area where it was affected by the 3/11 Earthquake, we are describing this as an ‘aftershock,’” said agency seismologist, Yasuhiro Yoshida.

Japan regularly experiences moderate size earthquakes in the area of the 2011 temblor several times a month, and JMA attributes most of them to the 2011 quake.

USGS wasn’t characterizing Tuesday’s quake as an aftershock, considering it a separate event.

Live NHK images from Iwate and Miyako Prefectures showed small fishing boats returning to port and captured the sounds of tsunami warning sirens.

The quake was initially measured at a 6.8 magnitude, but USGS later downgraded it to 6.7.

This story, which first appeared on NBCNews.com, is developing. Please check back for further updates.

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6.7 earthquake jolts northern Japan, triggers tsunami warning

Updated