Report on Galunggung (Indonesia) — August 1982
Scientific Event Alert Network Bulletin, vol. 7, no. 8 (August 1982)
Managing Editor: Lindsay McClelland.
Galunggung (Indonesia) Frequent explosions continue
Please cite this report as:
Global Volcanism Program, 1982. Report on Galunggung (Indonesia). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 7:8. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198208-263140.
7.25°S, 108.058°E; summit elev. 2168 m
All times are local (unless otherwise noted)
Frequent periods of explosive activity continued through early September . . . . A GMS image on 16 August at 1000 showed a plume that extended S then curved W to about 8°S, 100°E. By the time of the next available image, five hours later, feeding of the plume had ended and only remnants remained, S of Java.
After about ten days of quiescence, explosions resumed early 26 August. Antara radio reported that fire flashes were ejected from the crater for about six minutes starting at 0311, followed by roaring sounds that caused panic in Tasikmalaya. Around dawn, grayish ash rose 7-8 km above the summit and glowing material appeared to slide 200-500 m from the crater. "Flames" rose 50-100 m around the crater. Between 5 and 10 cm of ash fell in Garut. Ash darkened Bandung until 1030, reducing visibility to 3 m even in lighted areas. Residents of Jakarta (Indonesia's capital, about 170 km NW of Galunggung) remained indoors as ash thick enough to cover car windshields fell within a few minutes. GMS images indicated that ash ejection began about 0500 and lasted about two hours. Feeding had clearly stopped by 1000. A smaller explosion started just before midnight and appeared to be continuing on an image returned at 0100. On 30 August at 1015, Galunggung ejected a 5-6-km-high dense black and white eruption cloud followed by a series of thundering sounds and flashes. Heavy ashfall was reported near the volcano, and lighter ashfall occurred in Garut and in Bandung, where it began about 1300. Loud explosions accompanied by flashes of incandescence started again at 0353 on 31 August and continued until about 0930. Heavy tephra fall darkened villages a few km from the volcano and lapilli as large as marbles caused the collapse of two buildings. Satellite images showed a cloud, somewhat larger than many previously ejected by Galunggung, moving SSW. An explosion 2 September at 0400 was followed by a second, more powerful one at 0425. Heavy ashfalls disrupted traffic between Bandung and Cirebon (about 100 km from Bandung and 75 km NNE of the volcano) between 0900 and 1600. No additional explosions had been reported as of early September.
Cloud top temperatures determined from NOAA 7 polar orbiter infrared images have been compared with radiosonde temperature/altitude profiles above 5.95°N, 116.05°E to yield approximate cloud top altitudes (table 1).
Table 1. Galunggung cloud-top temperatures determined from NOAA 7 polar orbiting satellite images, 25 June-29 August 1982, with altitudes calculated from nearby radiosonde temperature/altitude profiles. Courtesy of Michael Matson, NOAA.[Skip text table]
DATE TIME TEMP (°C) ALTITUDE (KM) 25 Jun 1400 -61 12.5 14 Jul 0100 -72 16 (at tropopause) 1400 -72 16 (at tropopause) 29 Jul 0200 -53 11.5 13 Aug 1500 -72 15 16 Aug 1400 -58 no radiosonde data 29 Aug 1500 -72 15.5
Geologic Background. The forested slopes Galunggung in western Java are cut by a large horseshoe-shaped caldera breached to the SE that has served to channel the products of recent eruptions in that direction. The "Ten Thousand Hills of Tasikmalaya" dotting the plain below the volcano are debris-avalanche hummocks from the collapse that formed the breached caldera about 4200 years ago. Although historical eruptions, restricted to the central vent near the caldera headwall, have been infrequent, they have caused much devastation. The first historical eruption in 1822 produced pyroclastic flows and lahars that killed over 4000 people. More recently, a strong explosive eruption during 1982-1983 caused severe economic disruption to populated areas near the volcano.
Information Contacts: D. Haller, O. Karst, and M. Matson, NOAA; Antara News Agency, Jakarta; AFP; BBC.