A 6.0-magnitude earthquake struck Russia's Kamchatka Peninsula early Tuesday followed by a series of strong after-shocks, the US Geological Survey said.

The first quake struck at a depth of 33 kilometres (20 miles) at 0155 GMT, 136 kilometres east-southeast of the Russian city of Petropavlovsk-Kamchatsky, the USGS reported.

It was followed by three after-shocks, the strongest of which measured 5.9 magnitude at a depth of 44 kilometres, it added.

The Kamchatka branch of the Russian Academy of Sciences' geophysics service said on its website that the quake's magnitude measured 6.1, followed by aftershocks with a magnitude of up to 6.0.

The earthquake did not cause any casualties, the Kamchatka branch of the Emergency Situations ministry said in a statement.

"There is no risk of a tsunami. There are no casualties or damage."

The Kamchatka peninsula is where the Pacific tectonic plate meets part of the North American one, making the region one of the most seismically active in the world.

Magnitude 6.8 earthquake strikes off Chile: USGS
Santiago (AFP) May 20, 2013 - A magnitude 6.8 earthquake struck off the coast of Chile on Monday, the US Geological Survey said, with no immediate tsunami warning issued or reports of casualties or significant damage.

The quake occurred at 0949 GMT at a relatively shallow depth of 10 kilometers (six miles) and the epicenter was 1,538 kilometers south-southwest of the capital Santiago, the USGS said in its initial report.

The Pacific Tsunami Warning Center in Hawaii said historic data showed that no destructive widespread tsunami threat existed in the area -- but given the quake's strength, localized tsunamis were possible.

In February 2010, a massive 8.8-strength earthquake hit Chile's central Maule region, generating tsunami waves that killed more than 500 people and caused about $30 billion in damages.

Since then, further quakes have caused concern about what could be to come.

Chile sits on what geologists call the Pacific "Ring of Fire" due to its intense seismic activity.

In May last year more than half a million people in the country's central coastal region of Valparaiso participated in an earthquake and tsunami drill.