Mount Semeru Erupts: Eruptions Occur Dozens of Times, Status is Raised to Caution, Nearly 2,000 Residents Evacuate

Mount Semeru has experienced eruptions dozens of times since its status was upgraded from 'Alert' to 'Caution' or from Level III to Level IV by the Center for Volcanology and Geological Hazard Mitigation (PVMBG) on Sunday (04/12).

On Monday (05/12), the Semeru Volcano Observation Post (PPGA) officer, Mukdas Sofian, said that there had been nearly 30 eruptions during the observation period at 00.00-06.00 WIB.

Mount Semeru also experienced one hot cloud avalanche with an amplitude of 25 mm and an earthquake lasting 386 seconds.

"As a result of observing today's seismicity for six hours, Mount Semeru also experienced 29 eruptions with an amplitude of 11-22 mm and an earthquake duration of 65-120 seconds," he said in a written statement as quoted by the Antara news agency.

Semeru's activity was also recorded for six earthquakes with an amplitude of 1-8 mm and an earthquake duration of 50-140 seconds, one deep volcanic earthquake and one distant tectonic earthquake.

"Visual observations, Mount Semeru is clearly visible, observed white crater smoke with a thin to a moderate intensity that reaches 500 meters from the summit, then weak winds to the southwest," he said. 

Nearly 2,000 residents fled following the eruption of Mount Semeru in East Java on Sunday (04/12/2022), which sent hot clouds and lava into the surrounding areas.

This eruption prompted the authorities to raise the status to 'Caution'.

"With an increase in volcanic activity, the Center for Volcanology and Geological Hazard Mitigation (PVMBG) raised the status of Mount Semeru from 'Alert' to 'Caution' or from Level III to Level IV, as of 12.00 WIB today," said a spokesman for the Agency. National Disaster Management Agency (BNPB), Abdul Muhari, in a statement to journalists.

He explained that a hot avalanche cloud (APG) came from a pile of material at the tip of the lava tongue, which was about 800 meters from the summit (Jonggring Seloko Crater).

The hot clouds lasted until 06.00 WIB, with a sliding distance of seven kilometres from the summit towards Besuk Kobokan.

Then, seismic activity occurred on 4 December 2022 from 00.00 to 06.00 WIB, with details of eight earthquake eruptions and one APG earthquake that lasted until 06.00 WIB.

"This shows that the eruption activity and hot cloud avalanches at Mount Semeru are still very high. Besides the potential for hot clouds to occur, the potential for lava flows is still high considering the relatively high rainfall," said Muhari.

From the results of field monitoring by the PVMBG team and the Lumajang Regency Regional Disaster Management Agency (BPBD), the APG slide had reached 19 kilometres. It had even crossed the Gladak Perak Bridge.

"It's arrived at Gladak Perak," said Joko Sambang, Head of Emergency BPBD Lumajang Regency.

Semeru volcanic ash was also reported to soar in dark grey and black. Visibility was limited because the ash had started to fall, and it was raining around the site.

PVMBG asked the public not to do any activities in the southeastern sector along Besuk Kobokan, 13 kilometres from the eruption centre.

Outside of this distance, the community is expected not to carry out activities at a distance of 500 meters from the riverbank (river border) along Besuk Kobokan because it has the potential to be affected by the expansion of hot clouds and lava flows up to the distance of 17 kilometres from the summit.

People are also asked not to move within a five-kilometre radius from the crater or peak of Semeru because they are prone to the danger of throwing stones (incandescent).

In addition, the public is expected to be aware of hot cloud avalanches, lava avalanches, and lava along rivers or valleys that disgorge at the peak of Mount Semeru (especially along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat). It includes the potential lava in the small rivers, which is a tributary of Besuk Kobokan. Exactly a year ago, Mount Semeru also erupted, killing more than 50 people while thousands of houses were damaged.