A massive magnitude-8.8 earthquake struck near Concepcion, Chile, early today, the U.S. Geological Survey reported, shaking buildings and causing blackouts in parts of the capital of Santiago.
A tsunami warning was issued for Chile and Peru by the Pacific Tsunami Warning Center, and a tsunami watch was issued for Ecuador.
The earthquake struck in the sea 56 miles (90 km) northeast of Concepcion at a depth of 34 miles (55 km) at 7.30n (Malta time). Its magnitude was initially reported at 8.3 and 8.5, then fixed by the USGS at 8.8.
People streamed onto the streets of the Chilean capital, more than 200 miles (320 km) north of the epicenter, hugging each other and crying, a Reuters witness reported. Buildings shook and there were blackouts in parts of the city.
The Reuters witness reported very strong shaking lasting for 10 to 30 seconds.
A national emergency official told local radio the government was evaluating damage in and around Concepcion.
In 1960, Chile was hit by the world's biggest earthquake since records dating back to 1900, USGS data shows. The 9.5 magnitude quake devastated the south-central city of Valdivia, killing 1,655 people and sending a tsunami which battered Easter Island 2,300 miles (3,700 km) off Chile's Pacific seaboard and continued as far as Hawaii, Japan and the Philippines.
An 8.5 earthquake would make it bigger than the recent earthquake in Haiti.
Five facts about earthquakes and magnitude
Following are details about measuring the strength of earthquakes and related issues:
* Magnitude measures the size of an earthquake by the energy released at the source of the quake, and is determined from readings on seismographs.
Most seismologists now use "moment magnitude" for medium to large quakes. The scale is calculated differently from the older Richter scale, but the values produced are broadly comparable.
* The scale is logarithmic. Each whole number step in the magnitude scale corresponds to the release of about 31 times more energy than the amount associated with the preceding whole number value. So a magnitude 7.0 quake releases about 900 times more energy than a magnitude 5.0 tremor.
The scale is also open-ended. A quake of magnitude 2 is usually said to be the smallest normally felt by humans.
* The largest recorded earthquake occurred in Chile on May 22, 1960. It measured 9.5 and triggered a tsunami that swept across the Pacific Ocean, killing scores of people in Hawaii, Japan and elsewhere.
The quake that triggered the 2004 Indian Ocean tsunami had a magnitude of 9.15 and the earthquake that devastated Haiti's capital Port-au-Prince on Jan. 12 was rated at magnitude 7.
* Japan also uses a seismic intensity scale from 1 to 7 that measures the strength of seismic motion, and usually gets stronger the closer you get to the epicentre of an earthquake.
An earthquake that measures 1 on the Japanese scale is felt by only some people in a building. At 7, people find it impossible to move at will and most furniture moves violently.
* The epicentre is the point on the earth's surface vertically above the focus, or hypocentre, the point deep in the earth's crust where the earthquake is triggered. (Source: U.S. Geological Survey (www.usgs.gov) )