TEMPO.CO, Jakarta - Head of the eastern region volcano mitigation at the Volcanology and Geological Disaster Mitigation Center (PVMBG) Devy K. Syahbana said that Mount Anak Krakatau`s recent Surtseyan eruption was eerily similar to the 1927-1928 incident which also caused a tsunami.

“At the time, report shows that a tsunami also took place,” said Devy on Monday, December 24.

The mountain’s volcanic eruption change was further explained by PVMBG volcano mitigation head Wawan Irawan who said that mount Anak Krakatau has transformed from a strombolian to a Surtseyan type of eruption.

“The eruption is different now. It used to be a strombolian, like a fountain, but now it’s a Surtseyan,” said Wawan.

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According to Wawan, one of the causes that changed its type of eruption is the mountain’s main natural structure which partially collapsed that eventually triggered the tsunami on Saturday.

“One of the causes of the tsunami was one of the mountain’s section that suddenly collapsed and saw its materials avalanche into the ocean, which eventually created the tsunami,” Wawan explained.

The volcanic eruption change was heavily influenced by the fact that Mount Anak Krakatau itself was built by lava and pyroclastic flows of loose earth materials. The instability of its core could have separated because of the heavy flow of lava on top of it.

The PVMBG seismic detector that was installed at the Mount Anak Krakatau had died on Saturday, December 22, which is believed to be destroyed by the eruption combined with the suspected collapse of one of the mountain’s section.

AHMAD FIKRI (CONTRIBUTOR)