The Volcanology and Geological Hazard Mitigation Center (PVMBG) has increased the alert status of Mount Slamet in Central Java from normal to waspada (caution), the second-highest level, on Friday.
The alert status was raised after the PVMBG recorded at least 51,511 tremors from June 1 to Aug. 8, as well as five local tectonic earthquakes and 15 long-distance tectonic earthquakes in the same period, PVMBG head Kasbani said.
During the period, the center monitored that the mountain had been spewing white volcanic ash as high as 300 meters from the volcano’s crater, some 3,432 meters above sea level.
These data show that there has been an accumulation of magmatic energy from inside the mountain, he said.
“The energy has been increasing gradually, hence we decided to raise the alert status,” Kasbani told The Jakarta Post on Friday.
The status of Mt. Slamet had previously been “normal” since September 2015. The last volcanic activity was recorded from March to Aug. 2014, when an eruption took place.
The now increasing volcanic activity increased the possibility of a magmatic eruption with the volcano spewing out lava within a 2-kilometer radius from the peak, Kasbani said.
“There is also the possibility of a phreatic eruption,” he said.
The PVMBG further warned hikers and the public in general to pay attention to the PVMBG’s recommendations before conducting any activity around Mt. Slamet as well as other mountains with a high alert level.
As of Friday, there were 22 mountains across the country with high alert levels, 18 of which are at caution status and four others are on siaga (watch) status or the third-highest level of the four-tiered Indonesian volcano alert system. (dpk/afr)