Data from the Semeru Observation Post in Lumajang reported 10 eruptions between midnight and 8 a.m. on Nov. 7, with ash columns varying in height between 300 meters and 1,000 m above the mountain’s summit.

“The first eruption occurred at 12:24 a.m. WIB [Western Indonesian Time]. The plume reached 600 meters above the peak. It dispersed white to gray ash to the south and southwest. The seismic record showed a maximum amplitude of 22 [millimeters]. The duration was 122 seconds,” Semeru Observation Post official Ghufron Alwi said, as quoted by Antara news agency.

Another eruption occurred at 12:51 a.m., with an ash column 800 m high. The largest eruption occurred at 5:26 a.m., with an ash column reaching 1,000 m, as eruptions continued at intervals throughout Thursday morning.

Authorities have maintained Mt. Semeru's status at Level II for Waspada (advisory) on the four-tier volcano alert system, and advised people to avoid activities within a southeastern area stretching 8 km to the Besuk Kobokan River, the projected path of the lava flow.

Beyond this area, people should avoid activities within 500 m along the river due to the potential expansion of pyroclastic clouds and lahars up to 13 kilometers from the summit.

“Residents are also not allowed to conduct any activities in a radius of 3 kilometers from the summit of Mt. Semeru due to danger from burning rockfall,” said Ghufron.

In addition to Besuk Kobokan, residents are also asked to be alert to potential pyroclastic cloud, lava and lahar along the Besuk Kembar and Besuk Sat rivers and their tributaries.

 

Eruptions elsewhere

The status for Mt. Marapi in West Sumatra's Agam and Tanah Datar regencies has been raised to Level III for Siaga (watch) following intensified activities since late October.

Ash plumes as high as 2,000 m above the summit were detected on Oct. 27, with the latest observation recording a 1,500 m-high column of ash early morning on Wednesday.

The Energy and Mineral Resources Ministry’s Geology Agency has advised residents, climbers and visitors to avoid the area within a 4.5 km radius from Verbeek Crater, the epicenter of volcanic activities.

Meanwhile, the National Disaster Mitigation Agency (BNPB) has called on local administrations to immediately prepare measures for mitigating the potential impacts from a major eruption at Mt. Marapi.

These included, “if necessary, evacuating the residents immediately”, BNPB chief Lt. Gen Suharyanto told a virtual online press conference on Thursday.

In East Nusa Tenggara’s East Flores regency, Mount Lewotobi Laki-laki, currently at the highest status of Level IV for Awas (danger), erupted again on Thursday, emitting an ash column 2,500 m into the sky above the summit, or around 4,000 m above sea level.

The eruption occurred at 8:53 a.m. local time with a loud boom and pyroclastic flows extending 1 km to the northwest.

Authorities have established a 7 km exclusion zone around the stratovolcano, advising local residents to beware of potential lahars along rivers flowing from the mountain.