PVMBG reported that during 1 November-5 January white plumes rose at most 1.5 km above Slamet's crater. RSAM values fluctuated but decreased overall in December through 5 January. Deformation and geochemical data showed no significant changes. The Alert Level was lowered to 2 (on a scale of 1-4) on 5 January. Residents and tourists were warned to not approach the crater within a radius of 2 km.

Geological Summary. Slamet, Java's second highest volcano at 3428 m and one of its most active, has a cluster of about three dozen cinder cones on its lower SE-NE flanks and a single cinder cone on the western flank. It is composed of two overlapping edifices, an older basaltic-andesite to andesitic volcano on the west and a younger basaltic to basaltic-andesite one on the east. Gunung Malang II cinder cone on the upper E flank on the younger edifice fed a lava flow that extends 6 km E. Four craters occur at the summit of Gunung Slamet, with activity migrating to the SW over time. Historical eruptions, recorded since the 18th century, have originated from a 150-m-deep, 450-m-wide, steep-walled crater at the western part of the summit and have consisted of explosive eruptions generally lasting a few days to a few weeks.

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