Papandayan Volcano -
Reconnaissance in August 1998

In August 1998 Craig Roberts travelled to Indonesia to perform a reconnaissance of the volcano sites at which the SNAP hardware could be deployed for testing. Situated 70km west of Bandung, in west Java, Gunung Gede is a favourite destination for many hikers traversing the picturesque Mt. Gede-Pangrango National Park and was one of the candidate volcanoes for testing. Gede is also the closest active volcano to the archipelago's capital Jakarta, and for this reason gains greater significance as a tourist destination, but also as a potential hazard. Craig's account of the reconnaissance follows.

"It was necessary to set out at 3am, with headlamps, to reach the summit by 8am and catch a clear view of the surroundings before the daily morning cloud set in over the 2958m summit. Sulphur gas continuously belches from the main crater some 400 vertical metres directly below the summit. Unprotected instrumentation located in the path of this gas would simply corrode within 3 months. This became a critical issue as far as station location was concerned. Vulcanologist Ony Suganda from the Vulcanological Survey of Indonesia (VSI) warned of faulting in the area. Faults need to be avoided when locating the survey marks in order to ensure that the monitoring system measures volcanic deformation and not some other local movement. Line-of-sight to the observatory located 9km away at the base of the volcano was also a concern for radio communication between the GPS receivers located on the volcano and at the observatory."

"Three suitable sites were located but access to any of these was at least 5 hours by foot. Although it is an important volcano to study due to it's location and level of activity, it is anticipated that this prototype system will initially require a good deal of maintenance. I reserved judgement until I had visited another volcano, Papandayan."

"Gunung Papandayan erupted violently on the 11th and 12th August 1772, ejecting the summit portion of the mountain over 250 square kms of the surrounding the area. The north-eastern part of the mountain collapsed causing 2957 casualties and destroying 40 villages. Located 60km south east of Bandung and just 20km from the city of Garut, Papandayan is also a tourist destination as well as an eruptive threat. The VSI monitor this volcano with a continuous seismic station, periodic temperature and gas measures as well as by EDM and levelling. Visitors can park near the crater and walk just 10 minutes into a moonscape of sulphur gas clouds and bubbling volcanic mud. After a thorough reconnaissance of the area, it was decided to establish the SNAP GPS deformation monitoring system at Papandayan, principally because of it's easier access."

View of Gunung Papandayan showing missing cap blown away to create the crater.

Two points were located on the rim of the crater and one in the crater near the VSI seismic station. All stations were located next to the VSI's EDM sites, with line-of-sight to the observatory 8km away, on the flank of Papandayan. A fourth point was installed at the VSI observatory. Dr Hasan Abidin from the Department of Geodetic Engineering, Institute of Technology Bandung will conduct periodic static GPS surveys around the base of the volcano in order to establish the overall deformation behaviour of Papandayan.

Craig visited Indonesia again in July 1999 to install the first prototype network on the volcano. An additional test was conducted in early 2000 and mid-2001.