Report on Soputan (Indonesia) — February 1985

Scientific Event Alert Network Bulletin, vol. 10, no. 2 (February 1985)
Managing Editor: Lindsay McClelland

Soputan (Indonesia) Plumes from the May and August 1984 eruptions seen on satellite images

Please cite this report as:

Global Volcanism Program, 1985. Report on Soputan (Indonesia). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 10:2. Smithsonian Institution.

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1.112°N, 124.737°E; summit elev. 1785 m

All times are local (unless otherwise noted)

Yosihiro Sawada observed a series of plumes from the May and August 1984 eruptions of Soputan (table 2) on images from the GMS satellite. In 9:5, Adjat Sudradjat reported that Soputan erupted from 24 May at 2243 until 26 May at 0300, depositing tephra west of the volcano. A GMS infrared image 25 May at 2300 shows a nearly circular plume rising from the volcano. By the time of the next image, at 0500 the next day, a large eruption cloud was evident, but feeding from the volcano had ended 2 hours before. Six hours later, the plume was clearly detached from the volcano. A 5-hour explosive eruption of Soputan started 31 August at 0709 and lasted until about noon. A circular eruption column was evident less than an hour after the start of the activity (figure 1, left) and a large plume was visible 6 hours later, about 2 hours after the eruption ended (figure 1, right).

Table 2. Dimensions of plumes from Soputan determined from GMS images by Yosihiro Sawada.

[Skip text table]
    1984    Hour  Density  Width  Length  Movement  Minimum plume
                            (km)    (km)   direction  temperature
    25 May  2300  dense      60     60    circular      -79°C
    26 May  0500  dense     190    240       NW         -82°C
            1100  dense     160    330       NW         -70°C
            1700  diffuse   460    440        W
    31 Aug  0800  dense      30     40    circular      -74°C
            1400  dense     350    420        W         -75°C
            2000  diffuse   430    660        W
    01 Sep  0200  diffuse   430    360        W

Figure (see Caption) Figure 1. GMS infrared satellite images with arrows pointing to eruption clouds from Soputan 31 August 1984 at 0800 (top), and 1400 (bottom). Courtesy of Yosihiro Sawada.

Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano rises to 1784 m and is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.

Information Contacts: Y. Sawada, MRI, Tsukuba.