Rain after volcanic eruption hinders Indonesia's rescue efforts as death toll rises

Rescuers were searching for survivors Sunday on the slopes of the highest volcano on Indonesia's island of Java after it was rocked by an eruption that killed at least 14 people, as smoldering debris and thick mud hampered their efforts.

Mount Semeru in Lumajang district in East Java province spewed thick columns of ash more than 12,000 metres into the sky, and searing gas and lava flowed down its slopes after a sudden eruption Saturday triggered by heavy rains.

Villages and nearby towns were blanketed with falling ash and several hamlets were buried under tonnes of mud from volcanic debris.

Authorities warned the thousands of people who fled the volcano's wrath not to return during Sunday's lull in volcanic activity, but some villagers were desperate to check on livestock and possessions left behind. In several areas, everything — from the thinnest tree branch to couches and chairs inside homes — was caked with ash.

The debris and lava mixed with rainfall to form thick mud that destroyed the main bridge connecting Lumajang and the neighbouring district of Malang, as well as a smaller bridge, said Thoriqul Haq, the district chief in Lumajang.

The eruption eased pressure that had been building under a lave dome perched on the crater. But experts warned that the dome could still further collapse, causing an avalanche of the blistering gas and debris trapped beneath it.

A thunderstorm and days of rain, which eroded and partly collapsed the dome atop the 3,676-metre Semeru, triggered the eruption, said Eko Budi Lelono, who heads the geological survey centre.

He said flows of searing gas and lava travelled up to 800 metres to a nearby river at least twice on Saturday. People were advised to stay five kilometres from the crater's mouth, the agency said.

Television reports showed people screaming and running under a huge ash cloud, their faces wet from rain mixed with volcanic dust.

Despite an increase in activity since Wednesday, Semeru's alert status had remained at the third highest of four levels since it began erupting last year, and Indonesia's Volcanology Center for Geological Hazard Mitigation did not raise it this week, Lelono said.

Semeru, the stratovolcano, is also known as Mahameru, meaning "The Great Mountain" in Sanskrit. It has erupted many times over the last 200 years. Still, as with other volcanoes — it is one of 129 under watch in Indonesia, the world's largest archipelago — more than 62,000 people call Sumeru's fertile slopes home. The 3,676-metre volcano last erupted in January, with no casualties.

Indonesia, an archipelago of more than 270 million people, is prone to earthquakes and volcanic activity because it sits along the Pacific "Ring of Fire," a horseshoe-shaped series of fault lines. Currently 54 per cent of the country's nearly 270 million people live on Java, the country's most densely populated area.

Officials said earlier they had hoped they could avoid casualties by closely monitoring the volcano, but the death toll quickly rose from one late Saturday to 13 on Sunday morning.

National Disaster Mitigation Agency spokesperson Abdul Muhari said 57 people had been hospitalized, mostly with burns, respiratory problems and other injuries. He said rescuers were still searching for seven residents of Curah Kobokan village who were reported missing.