Indonesian authorities halted on Monday the search for 12 climbers after Mount Marapi volcano erupted again, unleashing a new burst of hot ash as high as 800 metres into the air, officials said.
The bodies of 11 climbers were recovered earlier in the day, but attempts to relocate others were hindered by the renewed activity, West Sumatra's Search and Rescue Agency head Abdul Malik said. The search operation would resume once conditions improved, he added.
A video released by the agency showed rescuers evacuating an injured climber on a stretcher off the mountain and into a waiting ambulance to be taken to hospital.
Marapi initially erupted on Sunday, spewing clouds of hot ash.
The volcano has stayed at the third highest of four alert levels since 2011, a level indicating above-normal volcanic activity and prohibiting climbers or villagers within three kilometres of the peak, said Hendra Gunawan, the head of the Center for Volcanology and Geological Disaster Mitigation.
"This means that there should be no climbing to the peak," Gunawan said, adding that climbers were only allowed below the danger zone, "but sometimes many of them broke the rules to fulfil their satisfaction to climb further."
Hundreds of villagers affected by smoke, ash
About 75 climbers had started their way up the nearly 2,900-metre mountain on Saturday and became stranded. Eight of those rescued Sunday were rushed to hospitals with burns and one also had a broken limb, said Hari Agustian, an official at the local Search and Rescue Agency in Padang, the West Sumatra provincial capital.
All of the climbers had registered at two command posts or online through West Sumatra's conservation agency before they climbed, Agustian said. It was possible others took illegal roads or local residents were active in the area, but it couldn't be confirmed, he said.
Marapi spewed thick columns of ash as high as 3,000 metres in Sunday's eruption and hot ash clouds spread several kilometres. Nearby villages and towns were blanketed by tonnes of volcanic debris. Volcanic dust and rain smeared the faces and hair of evacuated climbers, according to video on social media.
Falling ash blanketed several villages and blocked sunlight, and authorities distributed masks and urged residents to wear eyeglasses to protect them from volcanic ash. About 1,400 people live on Marapi's slopes in Rubai and Gobah Cumantiang, the nearest villages about five to six kilometres from the peak.
Merapi eruptions difficult to predict: analyst
Gunawan said that Sunday's eruption was not preceded by a significant increase in volcanic earthquakes. Deep volcanic earthquakes were only recorded three times between Nov. 16 and on Sunday, while the deformation equipment or tiltmeter on the peak showed a horizontal pattern on the radial axis and a slight inflation on the tangential axis.
"This shows that the eruption process is taking place quickly and the centre of pressure is very shallow, around the peak," he said.
Marapi has been observed regularly erupting since 2004 with a gap of two to four years, Gunawan said.
"Marapi eruptions are always sudden and difficult to detect using equipment because the source is near the surface," Gunawan said, "This eruption was not caused by the movement of magma."
West Sumatra's Search and Rescue Agency head Abdul Malik said rescuers found 11 bodies of climbers as they searched for those still missing and rescued three others Monday morning.
"The evacuation process of the bodies and survivors are still ongoing," he said, adding that rescuers are still searching for 12 climbers reportedly still missing.
Marapi has been active since a January eruption that caused no casualties. It is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific Basin.