Report on Batur (Indonesia) — June 1999

Bulletin of the Global Volcanism Network, vol. 24, no. 6 (June 1999)
Managing Editor: Richard Wunderman.

Batur (Indonesia) New eruption beginning in March; frequent explosions

Please cite this report as:

Global Volcanism Program, 1999. Report on Batur (Indonesia). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 24:6. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN199906-264010.

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Batur

Indonesia

8.242°S, 115.375°E; summit elev. 1717 m

All times are local (unless otherwise noted)


During the week of 9-15 March, white ash plumes rose 10-100 m above the crater. Booming noises were heard six times, and volcanic earthquakes increased drastically compared to the previous week (table 1). It was later determined that an ash eruption had begun on 15 March, sending bluish-white plumes 10-50 m high. On 17 March, two relatively recent craters merged when a connecting ridge collapsed as a result of earthquakes and small eruptions.

Table 1. Weekly seismicity recorded at Batur, March-July 1999. Types of events include volcanic A-type, volcanic B-type, tectonic, explosion earthquakes, and ash emissions (small explosion earthquakes). No data were available for the period 30 March-19 April. Maximum explosion amplitudes were reported as 2-26 mm during May; more typical, smaller amplitudes were 1.5-24 mm during May-July. Courtesy of VSI.

[Skip text table]
    Date        A-type  B-type  Tectonic  Explosion  Emission

    02-08 Mar       2      0        1          0          2
    09-15 Mar     106    241        1          0         26
    16-22 Mar       0     14        1        270          5
    23-29 Mar      --     --        1        299         --
    30 Mar-05 Apr  --     --       --         --         --
    06-12 Apr      --     --       --         --         --
    13-19 Apr      --     --       --         --         --
    20-26 Apr       1      2        2         79         35
    27 Apr-03 May   0      0        0         42         21
    04-10 May       0      0        0         26         39
    11-17 May       8      3        6         68         21
    18-24 May       0      0        3        337         47
    25-31 May       1      6        0        112         31
    01-07 Jun       3      4        1          6         19
    08-14 Jun      12      5        4          0         52
    15-21 Jun       4      6        4         85         48
    22-28 Jun       5     13        1        141         31
    29 Jun-05 Jul  10     10        2        171         50
    06-12 Jul       1      6        1        122         32
    13-19 Jul       0      0        1        206         14

Volcanic activity was dominated by emission events (small explosions) during the week of 23-29 March; the eruption plume was white-blue in color, rising 10-100 m above crater rim. Booming noises were heard three times on 22 March, but no glow was observed. Reports are not available for most of April, but during late April through the middle of May the seismic record was dominated by explosion events. Ash plumes, described as "white" or "white-bluish" were observed rising 50-100 m above the crater. Neither explosion sounds nor glow was observed.

Six explosions on 17 May ejected materials that fell around the crater. Another explosion on 25 May was accompanied by incandescent ejections that fell around the crater. Explosion sounds were heard on 17 occasions during the week of 25-31 May. "White ash emissions" rose only to 25 m during 1-14 June, but varied between 10 and 100 m the rest of the month. Similar activity continued through mid-July, and a variable rumbling noise was heard the week of 13-19 July.

Geologic Background. The historically active Batur volcano is located at the center of two concentric calderas NW of Agung volcano. The outer 10 x 13.5 km wide caldera was formed during eruption of the Bali (or Ubud) Ignimbrite about 29,300 years ago and now contains a caldera lake on its SE side, opposite the satellitic cone of 2152-m-high Gunung Abang, the topographic high of the Batur complex. The inner 6.4 x 9.4 km wide caldera was formed about 20,150 years ago during eruption of the Gunungkawi Ignimbrite. The SE wall of the inner caldera lies beneath Lake Batur; Batur cone has been constructed within the inner caldera to a height above the outer caldera rim. The 1717-m-high Batur stratovolcano has produced vents over much of the inner caldera, but a NE-SW fissure system has localized the Batur I, II, and III craters along the summit ridge. Historical eruptions have been characterized by mild-to-moderate explosive activity sometimes accompanied by lava emission. Basaltic lava flows from both summit and flank vents have reached the caldera floor and the shores of Lake Batur in historical time.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).