Mount Semeru in East Java erupted on Saturday. (Photo courtesy of BNPB)

One Dead, Two Missing, Dozens Injured as Mount Semeru Erupts


DECEMBER 05, 2021

Jakarta. Mount Semeru in East Java erupted on Saturday, sending a column of smoke and volcanic ashes into the air while triggering lahar on nearby rivers. At least one died, and dozens of others were injured with burns, while thousands of people fled their homes to several evacuation centers. 

Two sand miners were missing, and eight of their colleagues were also trapped at their mining site as lahar cut off their escape routes, Indah Amperawati Masdar, Lumajang’s deputy district head, said on Saturday.


The miners managed to send out a video message informing their condition before their signal was cut off.   

“We couldn't get in touch with them anymore because the phone couldn't be reached. This afternoon they sent a video asking for help, but the officers could not evacuate because lahar had reached their location. So we are waiting for it to subside. Hopefully, they are safe," Indah said. 

Villagers on the slope of Mt Semeru take refuge after an eruption on Dec. 4, 20210. (Antara Photo/Muhammad Sidkin Ali)
Villagers on the slope of Mt Semeru take refuge after an eruption on Dec. 4, 2021. (Antara Photo/Muhammad Sidkin Ali)

No Air Traffic Disruption

The Mount Semeru Volcano Observation Post reported the first sight of volcanic ash and the smell of sulfur around 3 p.m. local time, with a hot ash cloud falling to the southeast toward Pronojiwo sub-district Lumajang District. 

The Meteorology, Climatology, and Geophysics Agency (BMKG) predicts that volcanic ash from the eruption of Mount Semeru will tend to move west to the southwest over the next six hours.

AirNav Indonesia said that the Mount Semeru eruption had not impacted flights over the area or operations of nearby airports, including Juanda International Airport in Surabaya, East Java, Rosedi, AirNav’s corporate secretary said in a statement. 

Still, AirNav and Juanda Airport were conducting paper tests to measure the concentration of volcanic ash in the air, Rosedi said. A high ash concentration is hazardous to aviation, as it can clog the airplane jet engines. 

He said that AirNav had also rerouted flights to avoid flying near Mount Semeru. 

Quick Response

Authorities said thousands of people in Malang District and Lumajang District were affected by the eruption. They will need drinking water, face masks, proper clothing, ready-to-eat food and drinks, raincoats, tarpaulins, and blankets.

President Joko “Jokowi” Widodo has told the Head of the National Disaster Management Agency (BNPB), Maj. Gen. Suharyanto, to go to East Java and lead the mitigation effort immediately. 


"Under the direction of the President, we will immediately go to Lumajang at the first opportunity to ensure the handling of the emergency, especially regarding refugees, can be carried out appropriately and quickly," said Suharyanto.

He said BNPB had asked the Indonesian Military (TNI) for assistance in terms of personnel and equipment. 

Rain Triggered Eruption

Head of the Geological Agency of the Ministry of Energy and Mineral Resources (ESDM) Eko Budi Lelono suspected the eruption of Mount Semeru that occurred on Saturday afternoon was related to high rainfall around the mountain peak. The rain caused the lava lip to collapse, which triggered an eruption.

"It seems that there is indeed a connection with high rainfall, causing the lava lip to collapse, triggering an eruption," Eko said on Saturday. 

Eko arrived at the conclusion after seismic data only showed a low level of activities around Mount Semeru in the past few days.

"In terms of seismicity, it is relatively low. There is no indication of an increase in magma or surface rock level. The seismic activity of Mount Semeru is actually not excessive, which shows that the supply of magma is relatively normal," Eko said.