Mount Agung's eruption as seen from Besakih temple in Karangasem, Bali, Indonesia November 28, 2017. Antara Foto/Nyoman Budhiana via Reuters
Mount Agung's eruption as seen from Besakih temple in Karangasem, Bali, Indonesia November 28, 2017. Antara Foto/Nyoman Budhiana via Reuters

If its last eruption 44 years ago is any guide, the Mount Agung volcano could go on spewing ash and triggering mudflows for months, delivering a blow to Bali’s tourist industry that it has not felt since the 2002 terrorist bombings from which it took years to recover.

After a false alarm in September, the 3,000-meter Agung rumbled back to life on November 21, shifting into a pre-eruption magmatic state that a week later had forced 100,000 villagers from their homes, closed the island’s international airport and disrupted the travel plans of 60,000 airline passengers.

While much of the southern part of the island is well away from the danger of surging lahars, or mudflows, and pyroclastic avalanches of superheated rock and gas, the clouds of ash billowing from the glowing crater could become a constant concern to aviation.

What may worsen the danger is tropical cyclone Cempaka, now approaching the south coast of Java. The 1991 eruption of the Philippines’ Mt Pinatubo coincided with the arrival of Typhoon Yunya, bringing a cement-like mix of ash and rain that collapsed thousands of buildings.

A heavy ash fall could also do untold damage to crops and animal feed, clogging the traditional subak irrigation systems that supply water to the island’s picturesque rice terraces, which are a major tourist attraction in themselves.

Mount Agung volcano erupts as seen from Culik Village, Karangasem, Bali, Indonesia. Antara Foto/Nyoman Budhiana/ via REUTERS
Mount Agung volcano erupts as seen from Culik Village, Karangasem, Bali, Indonesia.
Antara Foto/Nyoman Budhiana/ via Reuters

Bali attracted more than 4.5 million tourists in the first nine months of 2017 and was on course for a year-end target of five million; the so-called Island of the Gods earns more than US$7 billion a year from tourism and contributes to half of the total number of foreign visitors to Indonesia.

The 2002 terrorist bombing of two nightclubs in Bali’s tourist strip, which claimed 202 lives, saw the number of foreign tourists plunge by 57%, leaving a vast number of Balinese jobless and the average hotel occupancy rate reduced from 70% to 18%.

For two years after Bali was a sad place, with domestic tourism and cottage industries the only lifeblood. Then, in 2005, just as business was starting to pick up, suicide bombers struck again, killing 20 people and delivering another economic setback.

Agung’s March 1963 eruption, followed by another violent event in May of that year, killed more than 1,500 people at a time when Indonesia was still not prepared to deal with disasters of this magnitude and Bali had not been discovered as the tourist mecca it is today.

Balinese Hindus walk after praying as Mount Agung erupts at Besakih Temple in Karangasem, Bali, Indonesia on November 26, 2017. REUTERS/Johannes P. Christo
Mount Agung erupts behind the Besakih Temple in Karangasem, Bali, Indonesia on November 26, 2017. Photo: Reuters/Johannes P. Christo

Indonesia’s disaster preparedness has improved significantly since the 2004 Aceh tsunami, with the National Disaster Management Agency (BNPB) playing a far more effective role over the past decade in coordinating early warning and emergency relief efforts.

The BNPB reports directly to the president and issues regular bulletins on the status of many of Indonesia’s 76 historically-active volcanoes – the most of any country in the world — drawing on information supplied by the Center for Volcanology and Disaster Hazard Mitigation (PVMBG).

Of that total, Agung is one of 59 volcanoes the PVMBG monitors regularly. And for good reason: Indonesia is second only to Japan in the number of recorded eruptions, but has suffered the highest casualties from lahars, pyroclastic flows and tsunamis, and has had the most evacuations.

Although only six other volcanoes, including Mount Sinabung in North Sumatra and Mount Semeru in East Java, are currently considered to be in an eruptive state, another 23 are under some form of alert status, many of them on populous Java where tens of millions live in proximity.

Villagers rescued by National Search and Rescue Agency are seen in a truck, due to the eruption of Mount Agung in Karangasem Bali resort island, Indonesia, November 27, 2017. REUTERS/Johannes P. Christo
Villagers evacuated by the National Search and Rescue Agency in Karangasem, Bali, November 27, 2017. Photo: Reuters/Johannes P. Christo

Smithsonian Institute records show that volcanic eruptions around Indonesia have claimed a conservative 170,000 victims since Europeans began to document seismic activity in the early 1500s; in many historical instances, the casualties are only given as “many,” without providing an estimate.

One of the worst was the 1815 eruption of Mount Tambora on the island of Sumbawa, lying to the east of Bali in the Nusa Tenggara island chain, although the 10,000 people who died in the blast itself were outnumbered by the 82,000 who subsequently succumbed to starvation and disease.

Agung erupted three times during the 1880s, without causing casualties. But the 1963 event measured a four on the Volcanic Explosivity Index (VEI) and continued until January 1964 with mud and pyroclastic flows killing 140 in one small village alone on the volcano’s eastern flank.

Lava, inside the crater of Mount Agung volcano, reflects off ash and clouds, while it erupts, as seen from Amed, Karangasem Regency, Bali, Indonesia November 30, 2017. Picture taken with long exposure. REUTERS/Darren Whiteside     TPX IMAGES OF THE DAY
Lava, inside the crater of Mount Agung volcano reflects off ash and clouds while it erupts on November 30, 2017. Photo: Reuters/Darren Whiteside

By comparison, Mount Pinatubo was a VEI 6, erupting on June 15, 1991 in a classic illustration of the explosive power of a volcano that has lain supposedly dormant for six centuries. Over the next few months it expelled 10 cubic kilometers of material.

Pinatubo claimed only 800 lives, but it matched the explosive force of the devastating 1883 eruption of Mount Krakatau, which killed 36,000 people, most of them from a 10-meter-high tsunami that battered both sides of the Sunda Strait.

Agung may not be in that category, but the impact of any full-scale eruption will be measured in economic terms. Geological studies show that volcanoes often tend to follow patterns set from previous eruptions, even those from centuries ago. So far, Agung appears to be doing just that.