OFUNATO, Japan (CBS) – An earthquake with a preliminary magnitude of 6.8 has struck off the coast of Japan, not far from where a 2011 earthquake and tsunami claimed the lives of more than 15,000 people.

The quake was reported at 1:12 p.m. Pacific time, 6:12 a.m. at the epicenter. The extent of damage or injuries is not known at this time. Earlier this week, scientists said they’ve recorded low frequency shaking on the ocean floor that may have been foreshadowing a larger earthquake similar to what was released during the 2011 earthquake.

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There was no initial tsunami risk to the United States, but Japan’s Meteorological Society reported the potential for a tsunami hitting the immediate region on mainland Japan.

The quake was centered about 200 miles north west of the Fukushima Daiichi Nuclear Power Station that was hit by a 8.9 magnitude quake which sparked what scientists are now calling the Honshu tsunami. That tsunami caused a meltdown and traveled across the Pacific Ocean at a rate of more than 400 miles per hour, eventually hitting Santa Cruz harbor. Tsunami warnings went up around the Pacific Rim as coastal residents in countries from Japan to the United States fled for higher ground.

When comparing to the 1906 San Francisco earthquake, USGS Seismologist Lucy Jones figured that Japan’s 2011 earthquake was equivalent to 30 of the devastating San Francisco earthquakes. That earthquake, a magnitude 7.7, struck just after 5 a.m. on April 18. It killed more than 3,000 people and left 225,000 homeless. A total of 28,000 buildings were destroyed.

COMPLETE QUAKE COVERAGE: CBS Earthquake Resource Center

This article will be updated as information warrants, and follow KPIX 5 on Twitter at @CBSSF or KCBS Radio on Twitter at @KCBSNews for updates on breaking news anytime.

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BAY AREA FAULTS: Interactive Map Of Local Faults

Strong earthquakes with an epicenter off the coast can trigger tsunamis, depending on the size and type of the fault movement. The Pacific Tsunami Warning Center tracks earthquake data for the West Coast.

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