Tsunami reshapes map of Asia

AFP[ WEDNESDAY, DECEMBER 29, 2004 12:00:12 AM]

LOS ANGELES: The earthquake that unleashed deadly tidal waves on Asia was so powerful that it made the Earth wobble on its axis and permanently altered the regional map, US geophysicists have said.

The 9-magnitude temblor that struck 250 km southeast of Sumatra Island on Sunday may have moved small islands as much as 20 metres, according to one expert.

“That earthquake has changed the map,” US geological survey (USGS) expert Ken Hudnut said. “Based on seismic modelling, some of the smaller islands off the southwest coast of Sumatra may have moved further southwest by about 20 metres. That is a lot of slip.”

The northwestern tip of the Indonesian territory of Sumatra may also have shifted to the southwest by around 36 metres, Mr Hudnut said.

In addition, the energy released as the two sides of the undersea fault slipped against each other made the Earth wobble on its axis, Mr Hudnut said.

“We can detect very slight motions of the Earth and I would expect that the Earth wobbled in its orbit when the earthquake occurred due the massive amount of energy exerted and the sudden shift in mass,” Mr Hudnut said.

However, Stuart Sipkin, of the USGS National Earthquake Information Centre in Golden Colorado, said it was more likely that the islands off Sumatra had risen higher out of the sea than they had moved laterally.

“In this case, the Indian plate dived below the Burma plate, causing uplift, so most of the motion to the islands would have been vertical, not horizontal,” Mr Sipkin said.