February 27, 2010 Chile Quake

Updated 03/10/2010

An 8.8 Magnitude quake shook the central coast of Chile on February 27, 2010 at 06:34 UTC, 3:34 AM local time. The epicenter was 70 miles north of the city of Concepcion, Chile and 200 mile SW of Santiago, Chile. It was followed by many strong aftershocks, as can be expected of such a large quake. In the 5 days following the quake there were over 25 aftershocks between 5.0 and 6.2 Magnitude. The quake triggered a tsunami that caused considerable damage in Chile, washing away fishing villages. People have been nervous that aftershocks might trigger more tsunamis or cause further damage to their homes.

The death toll stands at 800 from the earthquake and tsunami, with rescue efforts continuing. The most damage was in the area around Concepcion, Chile's second largest city, but Santiago and Valpariso, 200 miles to the north also experienced strong shaking and saw many damaged buildings. 1.5 million homes were damaged and as many as 2 million people affected by the quake. There has been considerable looting reported in Concepcion, especially supermarkets, but also other stores. Troops have been sent in to control it and a curfew imposed but some residents are also standing guard on their homes or businesses to protect them. Chile's President, Michelle Bachelet, has asserted that there are no shortages of food or fuel. Emergency vehicles are being given priority for fuel. Many people have simply left the area of greatest damage. The government is distributing emergency aid but many people living in the tent cities that have sprung up in Concepcion have not received any help 4 days after the quake.

The incoming President, Sebastian Pinera, says that he will make reconstruction his main priority, although the cost of $12 - $30 billion will require cutbacks in other areas.

The quake was caused by the subduction of the small Nazca tectonic plate under the South American plate. As the plates slip past each other they move haltingly, alternately sticking and slipping in different areas along the subduction zone. The largest earthquake known, the May 1960 9.5 M quake, was centered about 145 miles south of this quake. An 8.2 M quake hit 185 miles north of this one in 1906. 540 miles north of this quake there was a 8.5M quake in 1922. Different sections of the zone on both sides of this quake released the built up pressure every few decades. The pressure in this area was due to be released in a big quake. In a large subduction quake, a whole section of the subduction zone gives way at once. You can see this by looking at the location of the large aftershocks that followed the main quake. They occurred in a region 400 miles long centered at the epicenter of the main quake.

(See the Plate Tectonics page for more information on these processes.) The US Geological Survey (USGS) is an invaluable resource in understanding and tracking earthquakes. See the USGS summary of this quake.

See also the following news stories:

*Strong aftershocks hit quake-devastated central Chile (BBC 3/3/10)

*Aftermath of Chile Earthquake - Photos (San Francisco Chronicle)

*Chile quake survivor tells of chaos in Concepcion (BBC 3/3/10)

*Sebastian Pinera sees Chile plans jolted by earthquake(BBC 3/10/10)

*Chile's Social Earthquake (Global Alternatives)

*Researchers: Chile earthquake moved South American cities - literally (NY Daily News 3/9/10)