More deaths reported in Asia quake
Aid workers are finding those affected live in inaccessible areas.
Death toll is likely to rise from earthquake near Sumatra.
Scientists try to find out why two quakes had such different results.
(CNN) -- Survivors of the great earthquake that struck off Sumatra have used their hands to dig through rubble while searching for loved ones on the hard-hit Indonesian island of Nias.
The scene in the main town of Gunungsitoli was one of destruction, with numerous buildings in the city's commercial district have been flattened.
An Indonesian disaster official said about 200-300 people also died on the isolated Banyak island group just north of Nias.
"But we have not received further information about the homeless and wounded," Nerli Sulitiani, an official with the national disaster agency in the northern city of Medan, told Reuters.
On Nias, the coastal road linking the town with the airport 19 kilometers (12 miles) away was impassable due to a landslide that sent massive boulders cascading down on to the road.
The airport runway was also damaged, although it was open to light traffic.
Indonesian troops could be seen guarding official buildings in Gunungsitoli, but the overwhelming impression on the island was one in need of shelter, earth-moving equipment and emergency medical support.
In some areas of Gunungsitoli, survivors used their hands to sift through rubble in the absence of large equipment.
Many people slept in churches and mosques overnight, but most residents opted to sleep outside in the rain, rather than inside, CNN's Hugh Riminton reported from the scene.
Indonesian authorities have said 230 people were killed on Nias and another 100 died on nearby Simeulue Island.
Sumatra Governor Rizal Nurdin estimated the death toll had risen to 1,000, while government officials have said it could climb as high as 2,000, The Associated Press reported Wednesday.
Dino Patti Djalal, an Indonesian government spokesman, said about 150 buildings had collapsed.
"Many of the victims have fled to the hills they are so traumatized. Many have not returned to their homes yet," he said.
He said they are most in need of food, medicine and heavy equipment.
"Any medical teams would be helpful. We are already also employing the assistance of friendly countries to help the victims."
A geologist said Tuesday that it was luck that spared southern Asia from similar devastation to that caused by last year's earthquake and tsunamis in the same region.
Monday's quake, measured at 8.7 by the U.S. Geological Survey and 8.5 by the Pacific Tsunami Warning Center, sparked region-wide fears of a replay of December 26, setting off a tsunami that left more than 300,000 people dead or missing. (Full story)
The absence of an early warning system in the Indian Ocean has been decried as contributing to the large death toll. (Full story)
On Monday, local and national governments issued tsunami warnings and ordered evacuations of coastal areas, but soon canceled the alerts.
In Sydney, Australian Prime Minister John Howard said he was sending military transport aircraft and a supply ship to Indonesia to help the earthquake relief effort there. (Full story)
Howard said he offered medical facilities and emergency aid to Indonesian President Susilo Bambang Yudhoyono during a telephone call Tuesday.
Yudhoyono postponed a planned visit to Australia this week to tour the earthquake stricken areas.
He will now arrrive in Australia on Sunday for a three-day visit which will include discussion of the administration of a joint $1 billion relief and redevelopment package for the Indonesian province of Aceh, which was devasted by the December 26 disaster.
Earlier, U.S. President George W. Bush offered condolences to the victims of the most-recent earthquake and said American officials had offered assistance and were ready to provide it where needed.
"This earthquake has claimed lives and destroyed buildings in a part of Indonesia that is only now beginning to recover from the destruction caused by the tsunami three months ago," Bush said.
Monday's earthquake was smaller than the prior great quake, and the earth ruptured in a different direction, said Patrick Leahy of the U.S. Geological Survey.
"The quake yesterday, the rupture moved to the southeast," Leahy told CNN's "American Morning."
"So it ruptured in the opposite direction."
Though the earth moved along the same fault that moved in December, a number of factors reduced the impact, including the change in direction and the depth of the water, Leahy said.
"I believe we were lucky," he said. "Certainly the setting -- the so-called subduction zone earthquakes where the earth's tectonic plates are grinding against one another and actually one is sliding under the other -- is the typical place where one would get great earthquakes and ones that would create tsunamis." (Full story)
CNN's Hugh Riminton contributed to this story