Mount Dempo In South Sumatra Rises To Alert Level, People Don't Need To Panic

Aerial photo of Mount Dempo Pagar Alam using the MI8 helicopter belonging to the National Disaster Management Agency (BNPB) in Pagaralam, South Sumatra, Friday (18/9). (BETWEEN PHOTO/Nova Wahyudi/foc/15.)

PALEMBANG - The Center for Volcanology and Geological Hazard Mitigation (PVMBG) of the Geological Agency of the Ministry of Energy and Mineral Resources (ESDM) has raised the activity level of Mount Dempo in South Sumatra from level 1 (Normal) to level 2 (Alert).

This status increase has been effective since Friday, January 7, 2022, starting at 10.00 WIB.

Head of the Emergency Management Division of the South Sumatra Province Regional Disaster Management Agency, Ansori, in Palembang, Friday, January 7, said his agency had coordinated with the governments in Pagaralam, Lahat and Empat Lawang regarding the new status of Mount Dempo.

"BPBD asks various related parties to increase readiness considering that the volcano is no longer in a normal status," Ansori said as quoted by Antara.

However, he emphasized that all parties do not need to panic because the status level of this volcano is still at the Alert level because there are still two more levels, namely Alert and Caution.

"Indeed there have been activities, no longer normal status. But not yet on Alert or Alert, people don't need to panic and are easily provoked by rumors," he said.

Due to the increase in status, the public/visitors/tourists/climbers are not allowed to move and approach the area within a radius of 1 km from the crater, as well as the direction of the crater opening as far as 2 km to the north sector.

During the determination of this status, the Center for Volcanology and Geological Hazard Mitigation (PVMBG) will continue to evaluate the activity of Mount Dempo as an anticipatory step in the event of a more significant increase in volcanic activity.

Meanwhile, based on a letter sent by the Ministry of Energy and Mineral Resources to the government in South Sumatra, it is known that during December 1, 2021 to January 2, 2022, the volcano was clearly visible until it was covered in fog, when the weather was clear no gas/smoke gusts were observed from the crater/peak direction.

On January 3, 2022, gas gusts were observed from the direction of the thick white crater/peak with a height of about 150 meters from the top of the peak. The gusts did not last continuously, on January 4 to 6, 2022, no gas gusts were observed from the crater/peak direction.

The types of earthquakes recorded during the period 1 December 2021 to 6 January 2022 (Appendix 1) are Blowing Earthquakes, Low Frequency, Deep Volcanic, Local Tectonics, Distant Tectonics and Continuous Tremors. Continuous Tremor with an amplitude of 0.5 – 2 mm (predominantly 0.5 mm) was recorded from 4 to 6 January 2022.

Visual observations showed an increase in gas gust activity from the crater/peak, along with the appearance of tremor vibrations which indicated an increase in fluid (gas, liquid, solid rock) to a shallower depth.

The results of the Mount Dempo earthquake spectrogram from January 1 to 6, 2022 show that low-frequency earthquake energy has increased since January 3, 2022, which is associated with sudden fluid input (not gradual) and responds directly to the surface.

The current potential hazard is a phreatic eruption that produces ash and mud rain, as well as gusts of high concentration of volcanic gas whose distribution is limited around the crater/peak.

Phreatic eruptions can occur suddenly without being preceded by obvious symptoms of an increase. The radius affected by falling material can reach 1 km from the crater, and mud flows to the north sector 2 km in the direction of the crater opening.

Mount Dempo in South Sumatra geographically has a height of 3,049 meters above sea level.

Administratively, it belongs to the Pagaraam City area, and two other regencies, namely Lahat Regency and Empat Lawang Regency in South Sumatra.

The eruption of Mount Dempo has been recorded since 1818 and until now there have been 21 eruptions with the shortest eruption time being one year and the longest being 26 years.

The last eruption occurred on January 1, 2009 at 10:45:51 WIB. In 2021 there was an increase in seismicity in the form of the appearance of Continuous Tremor vibrations during April to September 2021.

The dominant character of the eruption of Mount Dempo is phreatic eruptions that occur suddenly, briefly, not preceded by clear precursor symptoms.

The eruption produces sulfur mud, pyroclastic material and water from the crater lake which can be life threatening. Eruption material is spread locally only around the eruption center/crater.