According to recent U.S. Geological Survey (USGS) data, the Russian Far East chain, the Kuril Islands, was hit by a massive 6.3 magnitude earthquake, with initial reports stating a 6.5. The epicenter was south of the archipelago, approximately 93 miles from the closest town, Severo-Kurilsk.

The quake occurred beneath the surface of the ocean, on its floor—exactly like the Great Tohoku Earthquake quake that resulted in tsunamis and nuclear reactor meltdowns and destroyed much of the Japanese east coast in March 2011.

In this case, there were no tsunamis. Although there are some discrepancies between the USGS estimates and those of the Geophysical Center of the Russian Academy of Sciences (which has a local branch that recorded the quake), the earthquake occurred at a depth somewhere between 11 and 46 miles beneath the surface of the ocean.

Severo-Kurilsk, and its roughly 2,500 inhabitants, felt the tremor at about 4.0 on the Richter scale. And there are no reports of any injuries or damage by any of the island chain’s 20,000 residents.

The island on which Severo-Kurilsk sits is very close to the Russian peninsula of Kamchatka. The Kuril Island chain was formed volcanically and stretches about 810 miles northeast from the Japanese island of Hokkaido to the aforementioned Russian Kamchatka Peninsula. The archipelago separates the Sea of Okhotsk from the Pacific Ocean.

The chain is comprised of 56 islands and hundreds of minor rocks and islets. The 20,000 residents are broken up into Ainu (indigenous, but not ethnic, Japanese islanders), ethnic Russians, and a variety of other former Soviet ethnicities.

There is a reasonably strong Russian military presence on the archipelago, due to both ethnic as well as political tensions that stretch back decades.  For example, ethnic Ukrainians make up a significant slice of the population.  The political unrest between Russia and Ukraine over the Russian annexation of Ukrainian territory accounts for some of this tension.

Further, there are ongoing territorial disputes between Russia and Japan over these islands, going back to the end of World War II.