Experts compare recent activity with Mount Agung's last eruption in 1963, which killed more than 1,000 people on the Indonesian island.
Threat of Bali volcano eruption forces 100,000 to flee danger area
Indonesian authorities ordered 100,000 people to flee Monday from an erupting volcano that forced the island's only international airport to close.
Over two months after it first began to rumble, Bali’s sacred volcano, Mount Agung has been exploding and hurling clouds of white and dark gray ash about 6,000 meters into the atmosphere since the weekend.
As plumes of steam and ash billowed skyward from the crater, liquid mudflow began to surge down the mountain, prompting authorities to urgently evacuate residents from within 10 km of the crater. which emits a scarlet glow at night from the lava welling up at its centre.
Its explosions can be heard about 12 km away on the island upon which most of Indonesia depends for tourist revenue.
On Saturday evening, when the plume hit 6,000 metres, some airlines began cancelling and diverting flights; on Monday morning, after the wind changed direction, bringing the ash cloud over the airport, Ngurah Rai, the island’s only airport.
With the ash cloud at 9,000 metres, it remains unclear whether the airport will reopen or which airlines will fly — but several airlines have cancelled all their flights for 24 hours.
Officials said cancellations could be extended,
As of Monday evening, over 445 flights and almost 60,000 passengers had been impacted. Aviation expert Gerry Soejatman said it was unlikely the situation would improve on Tuesday. “Looking at the current forecast, I don’t think it will open tomorrow as the wind is bringing the ash cloud over the airport,” he said.
Bali’s island location makes alternative routes out challenging.
“There are technically five different airports — four major — within reach: Bali, Lombok, Malang, Surabaya and Banyuwangi,” Soejatman said. “But they’re on three different islands — and Surabaya has its own problems with the deluge right now.”
Volcanologist Janine Krippner has been following Agung closely from her base in the US. “Agung is particularly difficult to predict because we have no geological data from previous eruptions, only what can be felt,” she said.
If Mount Agung follows the pattern of its last eruption, in 1963, there could be months of slow lava flow and ashfall followed by two very large explosions, months apart.
Alternatively, a large eruption could happen within days.
Indonesia's Vulcanology and Geological Disaster Mitigation Centre ,PVMBG, which is using drones, satellite imagery and other equipment, said predictions were difficult in the absence of instrumental recordings from the last eruption 54 years ago.
In 1963, the eruption of Mount Agung killed more than 1,000 people and razed several villages by hurling out hot ash and lava.
Recordings now show the northeast area of Agung's peak has swollen in recent weeks "indicating there is fairly strong pressure toward the surface", PVMBG said.
It warned that if a similar eruption occurred, it could send rocks bigger than fist-size up to 8 km from the summit and volcanic gas to a distance of 10 km within three minutes.
Some analysis, however, suggests the threat should not be as great this time because "energy at Mount Agung's magma chamber is not as big" and the ash column only around a quarter as high so far as the 20 km reached in 1963, Sutopo Purwo Nugroho, a spokesperson for Indonesia’s disaster mitigation agency.
“The most important thing for travellers is the wind direction,” she said. “The ash plume wasn’t an issue until the wind pushed it in the direction of the airport today.”
While visitors to Sidemen were dealing with a fine coating of ash alongside unusually spectacular volcano views, and ash particles were dirtying the curtains of Ubud, ashfall had yet to be visible in the tourist hubs of South Bali.
The ash cloud is already disrupting flights at Praya airport on neighbouring Lombok, while Soejatman thinks it likely the small, regional airport of Banyuwangi, just an hour from northwest Bali by boat, will close tomorrow afternoon.
Surabaya and Malang are at least 12 hours journey by car — and that’s when travelling by night. Trains on Java are slow.
Both volcanoes and wind direction are unpredictable, and experts are unwilling to predict how long the disruption could continue. “If you look at Merapi on Java, it went on for months,” Soejatman said. “But then Yogyakarta was covered in ash and everything went back to normal in a couple of days.”