Magnitude 6.9 earthquake shakes Russia's Kamchatka region; residents evacuate homes

A magnitude 6.9 earthquake struck near Ozernovskiy in Russia's Kamchatka region on Friday, the United States Geological Survey (USGS) said, shaking buildings in the region's main city and prompting some residents to leave their homes.

The USGS said the epicentre lay 76 km northeast of Ozernovskiy, at a depth of 143.2 km. It was initially determined to be at 52.01 degrees north latitude and 157.25 degrees east longitude. Such readings are preliminary and are often revised as more data becomes available.

Russia's state-run TASS news agency, citing the Kamchatka branch of the Russian Academy of Sciences' Geophysical Service, reported somewhat different figures. Seismologists there said the epicentre was on land, 156 km southwest of Petropavlovsk-Kamchatsky, at a depth of 138 km. Minor differences in location and depth between monitoring agencies are common in the hours after a strong earthquake.

Scientists in Kamchatka first estimated the magnitude at 6.5 and later revised it to 6.9. They said the earthquake was felt in Petropavlovsk-Kamchatsky with an instrumental intensity of up to four points on the scale used in Russia, comparable to a magnitude-5 tremor.

According to TASS, a number of residents of the regional administrative centre left their apartments because of the tremors. Inside residential buildings, eyewitnesses said light fixtures swung violently, doors slammed shut and tableware rattled. The tremor struck at 3:36 p.m. local time (3:36 a.m. GMT) and lasted about one minute, they said.

The reports did not mention any casualties, damage to buildings or tsunami warnings. Earthquakes at such depths — more than 100 km below the surface — generally release much of their energy before reaching the surface, and tend to produce less severe ground shaking than shallow earthquakes of the same magnitude.

Ozernovskiy is a small settlement on the western coast of the Kamchatka peninsula. The region is sparsely populated, with most residents living in and around Petropavlovsk-Kamchatsky, the administrative centre of Kamchatka Krai.

Kamchatka lies on the Pacific Ring of Fire, an arc of intense seismic and volcanic activity running along the edges of the Pacific Ocean. The peninsula, home to more than 300 volcanoes, records frequent earthquakes, and Russian authorities maintain a monitoring network to track activity and issue warnings when required.

Magnitude measures the energy released at the source of an earthquake, while intensity describes how strongly the shaking is felt at a particular place. The two are not the same: a single earthquake can be felt at different intensities in different locations, depending on distance from the epicentre, depth and local soil conditions.

Further verified details, including any official assessment of damage, were awaited at the time of this report.