CVGHM reported that during 23 August-21 September shallow volcanic earthquakes continued to be recorded at Tangkubanparahu but were less frequent. Other types of seismic signals also decreased. Based on seismicity, visual observations, deformation data, gas measurements, and soil and crater lake water temperatures, the Alert Level was lowered to 1 (on a scale of 1-4) on 21 September.

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)