The 8.8-magnitude quake, believed to be the fifth most powerful since seismic instruments were developed, shifted the city of Concepcion at least three metres to the west.

Comparing GPS locations known prior to the quake to those taken around ten days after, researchers from a number of institutions were able to show that other parts of South America also shifted, with the Chilean capital, Santiago, moving around 30 centimetres to the west-southwest.

The earthquake, which took place where the Nazca tectonic plate is being subducted below the South American plate, was so powerful that it may also have altered the length of each Earth day. Richard Gross, a scientist at NASA’s Jet Propulsion Laboratory, used a computer model to calculate the earthquake’s effect on the planet. His initial calculations showed a decline in day length of around 1.3 microseconds and a shift in the Earth’s fi gure axis (the axis around which the planet’s mass is balanced) of about eight centimetres.

And it seems likely that the quake will lead to an increase in volcanic eruptions in the area. In a pattern identified by Charles Darwin, among others, large earthquakes have been shown to trigger a rise in eruption rates.

May 2010