Once tremors detected, Bali volcano can erupt within hours: Volcanologist

Once tremors detected, Bali volcano can erupt within hours: Volcanologist

More signs are pointing towards a highly probable eruption of Mount Agung in Bali, Indonesia.

The sun sets behind Mount Agung on Oct 1, 2017. According to volcanologists, the eruption of Bali's sacred mountain is more probable than not. (Photo: Pichayada Promchertchoo) 

BALI, Indonesia: Prince Tjokorda Raka Putra can feel a message is coming from the god of Bali’s sacred mountain, Gunung Agung.

The last time he saw one was 54 years ago, on Feb 19, 1963. As witnessed by him and the people in Bali, the message was delivered with thick smoke, rocks and lava flying out of Mont Agung’s pinnacle.

“It’s like an atomic bomb atop the mountain’s peak. The plume rose very high, a massive amount of grey smoke,” the prince told Channel NewsAsia inside his palace in Klungkung.

“There were dust and sandstorms every day. Rocks rained down from the sky and ashes fell all over Bali.”

The eruption of Mount Agung in 1963 is one of the largest and most destructive in Indonesian history. It lasted for nearly a year, devastated countless villages and killed more than 1,100 people.

Fast forward to September 2017, the same thing could happen again, and probably soon. Volcanologists said it could only be a matter of hours, days or longer for the sacred mountain to blow. Many signs are pointing towards an irregular magma movement inside the volcanic edifice, as the hot fluid tries to reach the surface.

Since its previous eruption until recently, Mount Agung had reported zero volcanic earthquakes. Last week, however, more than 700 incidents were detected in one day, with the strongest magnitude measuring 4.3 on the Richter scale.

Such frequency and force is alarming for seismologists, as it has taken much less for other volcanoes to erupt.

Seismologists analyse data from a seismograph, which measures the magnitude of an earthquake.

“More than 700 earthquakes per day is already very high. If the number is increasing, it will create continued tremors. Then it may be a matter of hours before the eruption,” said Dr Devy Kamil Syahbana from the Centre for Volcanology and Geological Hazard Mitigation.

Besides the frequent quakes, his team has also detected the inflation of Mount Agung. They have also recorded significant changes on the crater’s surface. Hotspots are spreading everywhere, while cracks on the summit continue to emit white steam clouds, which have been intensifying over time.

Citing the accumulative magnitudes of the earthquakes, Dr Syahbana said the volume of Mount Agung’s intruded magma - the cause of volcanic earthquakes - is estimated at 15 million cubic metres (m3). Statistics show that if the volume of such magma goes above 6 million m3, an eruption is likely.

An example of a seismogram showing continued volcanic tremors. (The photo is not a representation of the ongoing volcanic activity on Mount Agung)

Still, there is hope.

“Global statistics say that’s 90 per cent of volcanoes. We still have 10 per cent chance that we won’t have the eruption. Of course, we hope for the best. But we need to prepare for the worst,” Dr Syahbana said.

Next to him, a seismograph was picking up a lot of vibration on Mount Agung. The rolling paper was full of many long, black lines indicating significant magnitudes.

“Before, it was just a straight line every day.”

WAIT, WATCH AND PRAY

More than 75,000 people have been evacuated from hazard-prone areas within a 12km radius of the active volcano. The decision was made based on the size of the affected area more than half a century ago.

A map shows the impact of Mount Agung's eruption in 1963-1964.

Between 1963 and 1964, about 280 million m3 of magma was ejected from Mount Agung. The lava flew as far as 14km to the north and 12km to the south, as well as southeast. Based on the government’s assessment, it is likely that if the eruption takes place again, it would be small at first.

“But it’s possible also that it’d be followed by harder eruptions,” Dr Syahbana added.

While the government is busy with its mitigation plan, many residents in Hindu-majority Bali prepare themselves for the uncertain future with faith in the god of Agung.

“We can only keep praying for strength to face what the god wills,” said Gusti Mangku Paruna Kubayan, a priest from Bali’s "Mother of Temple", Pura Besakih.

The temple complex was badly damaged by the 1963 eruption, given its location on the southwestern slope of Mount Agung. Based on Prince Tjokorda Raka’s account, the second eruption that year was bigger than the first, and destroyed all the shrines in the complex.

“There were dust and sandstorms every day. Rocks rained down from the sky and ashes fell all over Bali,” said Prince Tjokorda Raka Putra, referring to the 1963 eruption of Mount Agung. (Photo: Pichayada Promchertchoo)


Still, the magnitude of destruction in the 60s did not stop the priest from performing his act of faith.

The 52-year-old insisted on re-entering the sacred complex last week to perform a ritual, which he believes matters more than being sheltered inside Banjar Pekandelan Klod Temple with other evacuees.

Like many Balinese, the priest believes the god of Agung will let him know when the eruption is imminent.

The summit of Mount Agung is the highest point in Bali. During its previous eruption, the plume soared higher than 10,000 metres, according to Dr Syahbana.

“The temple has three sacred holes," he said. "One of them is believed to connect with the crater of Mount Agung. In 1963, smoke appeared there a few days before the eruption.”

He added: "Based on my faith, there will be a sign from the god if Mount Agung erupts.”

For volcanologists such as Dr Syahbana, however, there have already been plenty of signs.

“The probability of eruption at the moment is high. Still, this probability may change at any time. It depends on what the volcano wants.”

Source: CNA/de

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