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Report on Colo (Indonesia) — October 1983

Scientific Event Alert Network Bulletin, vol. 8, no. 10 (October 1983)
Managing Editor: Lindsay McClelland.

Colo (Indonesia) July- August explosion times, plume heights, and photos

Please cite this report as:

Global Volcanism Program, 1983. Report on Colo (Indonesia). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 8:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198310-266010.

Volcano Profile |  Complete Bulletin


Colo

Indonesia

0.162°S, 121.601°E; summit elev. 404 m

All times are local (unless otherwise noted)


A VSI team monitored the eruption from near the island [beginning 23 July, and observed 22 distinct explosions (table 2). Many, but not all of these explosions were detected by satellite (table 1).]

Table 2. Times of Una Una eruption clouds with heights estimated by VSI geologists [23 July-26 August 1983.].

Date Time Plume height (km)
23 Jul 1983 1623 10
25-26 Jul 1983 2325-0021 7.5
27 Jul 1983 0400-0605 7.5
27 Jul 1983 1500-2010 7
28 Jul 1983 0002-0045 8
28 Jul 1983 1630-1730 8
30 Jul 1983 1615-? 6
01 Aug 1983 1834-2000 7
01-02 Aug 1983 2130-0230 6
02 Aug 1983 0314-0600 8
02 Aug 1983 0800-0900 8
02-03 Aug 1983 1905-0200 5
04 Aug 1983 0915-1100 6
06 Aug 1983 1520-? 6
07 Aug 1983 1100-1900 10
11 Aug 1983 1115-1135 8
12 Aug 1983 0047-0147 9
18 Aug 1983 1013-1240 12
22 Aug 1983 1203-? 8
24 Aug 1983 2148-2220 4
25 Aug 1983 1847-2000 5.5
26 Aug 1983 1023-1139 10

Maurice Krafft visited Una Una in mid-Aug. He observed and photographed the 22 Aug explosion (table 2 and figure 3) and pyroclastic flow deposits from previous explosions (figure 4). The entire island had been devastated except for a narrow strip of undamaged vegetation and villages along the E coast.

Figure (see Caption) Figure 3. Explosion photographed from the S on 22 August 1983. Pyroclastic flows from this explosion continued 500 m beyond the SSW coast of the island and 1 km beyond the NNW coast. Courtesy of Maurice Krafft.
Figure (see Caption) Figure 4. Coconut trees uprooted by pyroclastic flows on the SE side of the island, photographed 19 August 1983. Pyroclastic flow deposits from the major 23 July explosion were 5 m thick on the island's SW side. A plume from the summit is in the background. Courtesy of Maurice Krafft.

Further Reference. Katili, J.A., and Sudradjat, A., 1984, The devastating 1983 eruption of Colo volcano, Una Una Island, central Sulawesi, Indonesia: Geologisches Jahrbuch, v. A75, p. 27-47.

Geologic Background. Colo volcano forms the isolated small island of Una Una in the middle of the Gulf of Tomini in northern Sulawesi. The broad, low volcano contains a 2-km-wide caldera with a small central cone. Only three eruptions have been recorded in historical time, but two of those caused widespread damage over much of the island. The last eruption, in 1983, produced pyroclastic flows that swept over most of the island shortly after all residents had been evacuated.

Information Contacts: A. Sudradjat, VSI; M. Krafft, Cernay.