Volcanic ash from Lewotobi volcano observed at 6 700 m (22 000 feet) a.s.l., Indonesia

Volcanic ash from Lewotobi volcano in Indonesia was observed at 6 700 m (22 000 feet) above sea level at 00:40 UTC on October 15, 2025. The advisory was issued by the Darwin VAAC at 01:00 UTC on the same day.

According to the VAAC advisory, volcanic ash was visible at altitudes up to flight level 180 (approximately 5 500 m or 18 000 feet), with ash near the summit reaching flight level 220 (approximately 6 700 m or 22 000 feet) in light winds. The ash cloud was moving northwest at approximately 19 km/h (12 mph) and was discernible on Himawari-8 satellite imagery. The ash observed at flight level 180 is expected to dissipate within 6 to 12 hours. The current Aviation Color Code is Red.

The Smithsonian / USGS Weekly Volcanic Activity Report for September 24–30, 2025, noted that daily white-and-gray or gray ash plumes with variable densities at Lewotobi Laki-laki rose as high as 2 000 m (6 600 feet) above the summit and drifted in multiple directions. The report also mentioned that volcanic ash caused the closure of Fransiskus Xaverius Seda Airport, located 60 km (37 miles) west, on September 26 and 27. The Alert Level was lowered to 3 on September 29, 2025, with a public warning to stay 6 km (3.7 miles) from the center of Laki-laki.

Lewotobi consists of two stratovolcanoes, Lewotobi Lakilaki (male) and Lewotobi Perempuan (female), located on eastern Flores Island. The volcano is known for producing explosive eruptions, with primary hazards including ashfall and pyroclastic flows. The nearest significant population centers are small villages and towns on Flores Island, with Maumere city situated about 70 km (43 miles) north-northwest, placing some communities at risk from large eruptions and associated volcanic hazards.