Russia Meteor Shock 'Went Twice Around Earth'

The shockwaves from the meteor which exploded over Russia in February travelled twice around the Earth, according to scientists.

More than 1,000 people were injured when the 10,000 ton object - larger than a double-decker bus - burnt up in the skies above Chelyabinsk in Siberia.

The tremors from the meteor were recorded at 20 'infrasonic' monitoring stations, which are designed to detect nuclear weapon tests, across the world.

Writing in the journal Geophysical Research Letters , scientists said it was the first time the stations had detected "multiple arrivals involving waves that travelled twice round the globe".

"It generated infrasound returns, after circling the globe, at distances up to (approximately) 85,000 km, and was detected at 20 infrasonic stations of the global International Monitoring System (IMS)," said researchers.

The explosive energy of the blast is estimated to be equivalent to 460 kilotons of TNT. The force of the Hiroshima bomb dropped during the Second World War was about 16 kilotons.

"This extraordinary event is, together with the 1908 Tunguska fireball, among the most energetic events ever instrumentally recorded," scientists concluded.

The 1908 event, which occurred over a more remote area of Siberia, decimated tens of millions of trees over hundreds of square miles.

A far larger comet or meteor, in the region of 100 metres, is thought to have been responsible.

The Chelyabinsk meteor blazed across Russian skies on February 15 this year and saw a number of people injured by flying glass after windows were blown in.

Witnesses in the city, which has a population of more than one million, described feeling a pressure wave and hearing explosions overhead as the object hurtled towards Earth.

The meteor entered the Earth's atmosphere at 33,000mph (54,000kph) - 15 times the speed of a rifle bullet, according to the Russian Academy of Sciences.