The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported increased seismicity at Slamet in a 29 November press release. An increase in the number of deep volcanic earthquakes in May was followed by increases in the numbers of low-frequency earthquakes and earthquakes indicating emissions during May-August, more frequent shallow volcanic earthquakes during June-July, and increased tremor amplitude during late September. Earthquakes indicating emissions, low-frequency earthquakes, non-harmonic tremor, and continuous tremor continued to be recorded during November. A non-harmonic tremor signal recorded during 0735-0746 on 28 November was followed by an increase in the amplitude of continuous tremor. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the summit.

Geological Summary. Slamet is one of Java's most active volcanoes. It has a cluster of about three dozen cinder cones on its lower SE-NE flanks and a single cinder cone on the W 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. 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)