The Indonesian islands of Sumatra moved only 20 centimeters (or 7.9 inches) on average after last month's Asian earthquake and tsunami, and not dozens of meters as previously feared, media reported yesterday, quoting calculations by the Danish Space Centre.

The new numbers, reported on television channel TV2's website, vary greatly from reports in the days following the devastating Dec 26 earthquake that the tip of the Sumatra island may have moved by as much as 36 meters.

US Geological Survey scientist Ken Hudnut told AFP on Dec 27 that some of the smaller Sumatra islands may have moved about 20 meters while the northeastern tip of the Indonesian territory could have slid about 36 meters to the southwest after the quake, which measured 9.0 on the Richter scale.

GPS satellite system

Scientists Shfaqat Abbas Khan and Olafur Gudmundsson of the Danish Space Center, who used a GPS satellite system to determine the extent of the plate movement following the earthquake, have however since found that the island did not move more than 20 centimeters on average.

"For the Sumatra earthquake there were horizontal moves of about seven meters around the crack area. But that area is about 200km to 300km west of Sumatra, so Sumatra itself could only have moved about 20 centimeters," Khan told TV2.

The two Danish scientists' findings also contradicts a report from the Malaysian navy published yesterday stating that the depth in certain stretches of the narrow Malacca Straits, one of the world's busiest shipping lanes, had changed by as much as two meters after the quake.

"The GPS observations show that the Malacca Straits near Sumatra basically hasn't changed," Khan said.