The death toll from a tsunami and a volcano rose to more than 300 Wednesday as more victims of Indonesia's double disasters were found and an official said a warning system installed after a deadly ocean wave in 2004 had broken from a lack of maintenance.

Hundreds were still missing after Monday's tsunami struck the remote Mentawi islands off western Sumatra, where officials were only beginning to chart the scope of the devastation. At least 311 people died as the huge wave, triggered by an undersea earthquake, washed away wooden and bamboo homes, displacing more than 20,000 people.

About 800 miles (1,300 kilometers) to the east in central Java, the Mount Merapi volcano was mostly quiet but still a threat after Tuesday's eruption that sent searing ash clouds into the air, killing at least 30 people and injuring 17. Among the dead was a revered elder who had refused to leave his ceremonial post as caretaker of the mountain's spirits.

President Susilo Bambang Yudhoyono rushed home from a state visit to Vietnam to deal with the catastrophes, which struck within 24 hours along different points of the Pacific "Ring of Fire," a series of fault lines prone to earthquakes and volcanic activity.

The first cargo plane loaded with tents, medicine, food and clothes landed Wednesday in the tsunami-hit area, said disaster official Ade Edward.

Huge swaths of land were underwater and homes were torn apart by the 10-foot (3-meter) wave that hit Pagai Utara island in the Indian Ocean south of Sumatra. One house lay tilted, resting on the edge of its red roof, with tires and slabs of concrete piled up on the surrounding sand.

Hundreds of homes were washed away in about 20 villages, displacing more than 20,000 people, Edward said. Many were seeking shelter in makeshift emergency camps or with family and friends.

Vice President Boediono toured devastated villages on Pagai Utara and met with survivors and local officials, his office said. At one point, he paused solemnly in front of several corpses in body bags.

The charity SurfAid International is getting "grim news" from village contacts, said Andrew Judge, head of the group founded by surfers who have been helping deliver aid. He said he is hearing of "more death, large numbers of deaths in some villages."