Relief efforts are underway on Indonesia's Sumatra Island after the country was hit by four powerful earthquakes and a succession of large aftershocks in less than 24 hours. The tremors toppled buildings, killed several people and injured dozens more. VOA's Nancy-Amelia Collins in Jakarta has more.

A local girl at her house destroyed by earthquake in Bengkulu, Sumatra island, 13 Sep 2007

Officials say dozens have been injured, several people killed, and many buildings have been destroyed.

Sutrisno, the head of Indonesia's National Disaster Coordinating Agency, says representatives of various government ministries are already on the scene.

"They will have a meeting with the vice governor there and they are going to make also a rapid, very rapid assessment regarding a needs assessment and damage assessment ... But meanwhile, we are also in here still collecting the food for the relief assistance, like food and medicine, and we will send there by special aircraft, by Hercules," said Sutrisno.

Sumatra has been jolted by four powerful earthquakes since late Wednesday.

The U.S. Geological Survey says the first was centered about 105 kilometers southwest of Bengkulu, a major city on Sumatra's southwestern coast. At a magnitude of 8.4, it was the most powerful earthquake to strike anywhere in the world this year.

Two more quakes followed early Thursday - the first of 7.9 magnitude, and a second several hours later measured 7.1. There have also been more than 20 sizable aftershocks, all situated along the coastline between Bengkulu and the city of Padang. A fourth serious quake struck late Thursday north of Indonesia's Sulawesi Island, far to the east of Sumatra.

Indonesia issued five separate tsunami warnings during the period, and two small tsunamis were reported, but neither caused any serious damage or injury. An Indonesian official said that despite the number and severity of the tremors, injuries have been far fewer than feared.

Country Director Craig Redmond, of Mercy Corps, an international relief organization, says aid teams have reported considerable physical destruction.

"Lots of houses destroyed, [there are] needs for shelter, things like that," he said. "Right now they are up there seeing where we can add value and how we can coordinate with local officials."

The 9.1 magnitude quake that devastated Indonesia's Aceh province in December 2004 and triggered the Indian Ocean tsunami occurred not far north of the latest tremors off Sumatra's west coast.

The U.S. Geological Service reports that more than 283,000 people in a dozen countries were killed in that disaster. More than half of the victims died in Aceh.

Indonesia's presidential spokesman, Andi Mallerangeng, says these disasters have made the nation stronger.

"We know that we are living in the ring of fire with all different kinds of natural phenomenon... But I think we are a strong nation, every time we are getting stronger. We deal with the situation," he said.

Indonesia lies on the "Pacific Ring of Fire", a geologically active area that is prone to earthquakes and volcanic eruptions.