CVGHM reported that on 21 February tremor increased at Tangkubanparahu and diffuse ash emissions rose from Ratu Crater. Based on the seismicity, visual observations, and temperature increases of the land around the crater, the Alert Level was raised to 2 (on a scale of 1-4) and visitors were reminded not to approach the crater within a radius of 1.5 km.

Geological Summary. Gunung Tangkuban Parahu is a broad stratovolcano overlooking Indonesia's former capital city of Bandung. The volcano was constructed within the 6 x 8 km Pleistocene Sunda caldera, which formed about 190,000 years ago. The volcano's low profile is the subject of legends referring to the mountain of the "upturned boat." The Sunda caldera rim forms a prominent ridge on the western side; elsewhere the rim is largely buried by deposits of the current volcano. The dominantly small phreatic eruptions recorded since the 19th century have originated from several nested craters within an elliptical 1 x 1.5 km summit depression.

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