The Volcanology and Geological Hazard Mitigation Center (PVMBG) has noted that there are 20 volcanoes with above normal levels of activity across the country.

"One of them has the status of awas [danger], two are on siaga [watch] and the remaining 17 mountains are on waspada [caution]. The awas is Mount Sinabung [North Sumatra], and the siaga are Mount Agung [Bali] and Mount Soputan [North Sulawesi]," said Kristianto, PVMBG's head of the western region volcanic mitigation subsector, as quoted by tempo.co.

Kristianto said a number of volcanoes were popular tourist destinations during the Christmas and New Year holiday period. The PVMBG has coordinated with the respective tourist area managers, he added.

"For Mount Tangkubanparahu [West Java], Dieng [Central Java], Papandayan [West Java], Gede [West Java] and Bromo [East Java], we have given the direction to remain cautious and coordinate with us at the PVMBG or with the Volcano Observation Post, which is on stand-by to provide information," Kristianto said.

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He also cautioned that volcanoes could erupt with little or no warning. "It's not that there are no signs, but they are short, and not obvious," he said.

A number of volcanoes have such characteristics, including Mount Tangkubanparahu and Mount Papandayan. "Mount Tangkubanparahu in 2013, for example, issued several phreatic eruptions that were not preceded by obvious signs," he said.

Kristianto said the phreatic eruptions produced a burst of material that fell around the crater of Mount Tangkubanparahu. "It is imaginable that if it happened during daytime, it could cause a panic, and maybe someone could get hit. In general, the material thrown out by phreatic eruptions is not hot, but it's the aspect of panic that could actually cause new problems. This is what needs to be watched out for," he said.

He added that the PVMBG had already established intensive communication to anticipate such events, especially during this holiday season. "Communication between our managers and us from the PVMBG, as well as officials in the Volcano Observation Post, has been intensified. Especially at Tangkubanparahu, we have arranged for information to be disseminated," he said. (liz/kes)