CVGHM reported that during 13-18 May diffuse white plumes from Sirung rose 10-50 m above the crater. Seismicity was elevated during 12-17 May then decreased through 23 May, although levels remained above background. On 25 May the Alert Level was lowered to 2 (on a scale of 1-4).

Geological Summary. Sirung is located at the NE end of a volcanic massif with multiple centers that extends 14 km NE from the southern end of Pantar Island. The volcano is truncated by a 2-km-wide caldera whose floor often contains one or more small lakes. Much of the volcano is constructed of basaltic lava flows, and the Gunung Sirung lava dome forms the high point on the caldera's western rim. A number of phreatic eruptions occurred from vents within the caldera during the 20th century. Forested Gunung Topaki, the high point of the volcanic chain, has a small summit crater and lies ~3.5 km SW of the active crater area.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)