Central Chile still runs the risk of a large earthquake close to the site of last February's Magnitude 8.8 event, scientists say.

It was widely speculated at the time that the tremor would have released pressure on the fault running through the country's Maule region. But a new study finds the strain has not been released markedly, and has in fact increased in places.

The Nature Geoscience report should aid preparedness, researchers say. Maule's M8.8 event occurred at the converging boundary between the Nazca and South American tectonic plates. These vast slabs of the Earth's surface are grinding past each other at a rate of centimetres per year.

The quake's epicentre was about 100km from Concepcion city, just off shore and at a depth of about 35km.

It caused widespread damage to buildings and other infrastructure. The tremor also set off tsunami that inundated the coastline. More than 500 people are known to have been killed. The quake occurred in what scientists referred to at the time as a "seismic gap" - a zone along the tectonic plate interface that had not experienced a major quake since the one witnessed by Charles Darwin in 1835 during his famous Beagle expedition. The assumption had been therefore that Maule's M8.8 quake would have released the strain that had built up in the rocks over 175 years. [ BBC NEWS ]