PVMBG Monitors 24 Hours Of Increasing Volcanic Activity In Indonesia

JAKARTA - The Center for Volcanology and Geological Disaster Mitigation (PVMBG) of the Geological Agency of the Ministry of Energy and Mineral Resources monitors active volcanoes in Indonesia 24 hours a day, which shows increased activity in the last few days, through the Volcano Observation Post (PGA).

"To date, 68 volcanoes are monitored continuously through 75 volcano observation posts throughout Indonesia, as one way of mitigating volcanic eruptions. This activity is monitored continuously for 24 hours," said Head of PVMBG of the Ministry of Energy and Mineral Resources Hendra Gunawan in statement reported by ANTARA, Tuesday, December 5.

According to him, an eruption could have a wide impact on the surrounding population, of which 4.5 million people live and carry out activities around active volcanoes, so the risk of disaster is very large.

"We routinely convey information and coordinate regarding volcanic activity to relevant stakeholders," he explained.

Based on surveillance and monitoring, until the end of November 2023, three volcanoes were recorded at Level III (Alert), namely Anak Krakatau, Merapi, and Semeru, and at Level II (Alert) there were 18 volcanoes.

Meanwhile, there are 47 Level I (Normal) volcanoes whose condition has not shown an increase in activity.

Hendra said that the amount of volcanic activity in Indonesia is influenced by Indonesia's location at the meeting point of three active tectonic plates, namely the Eurasian, Pacific and Indo-Australian, which are moving towards each other.

"The subduction or subduction process results in the melting of the earth's crustal rocks, the melted rock part has a lighter specific gravity than the surrounding rock, so it moves to float towards the surface, then forms a volcano," he said.

It continues the process of subduction and melting of crustal rock mixed with mantle rock, part by part, running continuously, resulting in periodic eruptions of volcanoes.

In Indonesia there are 127 volcanoes or 13 percent of the number of volcanoes in the world. The volcano forms an archipelago of islands, from Sumatra, Java, Bali, Nusa Tenggara, Maluku, North Maluku, northern Sulawesi and the Sangir Talaud Islands.

Mount Lokon and Anak Krakatoa

Hendra explained that several volcanoes are currently showing increased volcanic activity, including Mount Lokon and Mount Anak Krakatau.

Mount Lokon is located in Tomohon City, North Sulawesi. Mount Lokon's volcanic activity is monitored visually and instrumentally from the Volcano Observation Post (PPGA) in Kakaskasen Village, North Tomohon District, Tomohon City. Mount Lokon's activity level currently remains alert.

Notes from Mount Lokon Post officers show an increase in crater smoke activity since 00.00–06.00 WITA as high as 25-150 m from the Tompaluan crater, which was followed by an increase in seismicity in the form of 25 shallow volcanic earthquakes, 5 deep volcanic earthquakes, 3 gust earthquakes, and 3 times distant tectonic earthquakes.

Based on visual and instrumental data, it is indicated that there was an increase in pressure in the shallow part (surface) after a shallow volcanic earthquake was recorded which was associated with the release of exhaled gas.

The potential threat of danger from Mount Lokon's activity at this time is that a sudden phreatic eruption (eruption caused by contact of magma with hydrothermal water) can be followed by a phreatomagmatic-magmatic eruption.

According to Hendra, eruptions can be accompanied by ejections of incandescent material measuring lapilli to lumps and thick ash rain with or without a sudden flow of hot eruptive clouds.

"In addition to being aware of the potential for lava flooding in rivers that originate at the peak, people are advised to stay indoors and when outside the house they are advised to use nose, mouth (mask) and eye protection (goggles)," he added.

For Mount Anak Krakatau, Lampung, Hendra said that an eruption occurred on December 5 2023 at 16.25 WIB with the height of the ash column observed to be 1,000 m above the peak (1,157 m above sea level).

"The ash column was observed to be gray in color with a thick intensity leaning towards the northwest. This eruption was recorded on a seismogram with a maximum amplitude of 70 mm and a duration of 49 seconds and no boom was heard," he explained.

Currently, Mount Anak Krakatau is at Alert Level with recommendations for the public/visitors/tourists/climbers not to approach it or carry out activities within a 5 km radius of the active crater.