PVMBG reported that on 14 February, the day after a large eruption at Kelut that began at 2250 on 13 February, gray-to-black plumes rose 400-600 m above the crater. On 15 February grayish white plumes rose as high as 3 km. During 16-20 February white plumes rose as high as 1 km and drifted N, NE, and E. Heavy rain on 18 February caused lahars in Ngobo, Mangli (Kediri, 35 km WNW), Bladak (Blitar, 20 km SW), and Konto (Malang, 35 km E). BNPB noted that the lahars flooded five houses and one mosque, and destroyed two homes and one bridge.

The report noted that four out of the five seismic stations monitoring Kelut were destroyed during the eruption. The one remaining station, 5 km away, recorded declining seismicity during 14-20 February. Two more seismic stations were installed, 2-3 km from the crater, on 16 February. The Alert Level was lowered to 3 on 20 February. Visitors and residents were prohibited from approaching the crater within a radius of 5 km; residents outside of the 5-km restricted zone were permitted to return home.

Geological Summary. The relatively inconspicuous Kelud stratovolcano contains a summit crater lake that has been the source of some of Indonesia's most deadly eruptions. A cluster of summit lava domes cut by numerous craters has given the summit a very irregular profile. Satellitic cones and lava domes are also located low on the E, W, and SSW flanks. Eruptive activity has in general migrated in a clockwise direction around the summit vent complex. More than 30 eruptions have been recorded since 1000 CE. The ejection of water from the crater lake during the typically short but violent eruptions has created pyroclastic flows and lahars that have caused widespread fatalities and destruction. After more than 5,000 people were killed during an eruption in 1919, an engineering project to drain the crater lake lowered the surface by more than 50 m. The 1951 eruption deepened the crater by 70 m, leaving 50 million cubic meters of water after the damaged drainage tunnels were repaired. Following more than 200 deaths in the 1966 eruption, a new deeper tunnel was constructed, and the lake's volume before the 1990 eruption was only about 1 million cubic meters.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Badan Nacional Penanggulangan Bencana (BNPB)