- Sumatra has many active volcanoes - Photo by Tom Casadevell
A volcano has erupted in Indonesia after having reportedly been inactive (dormant) for centuries. Reuters news agency reported that Mount Sinabung erupted on 29 August 2010 and quoted the head of Indonesia’s vulcanology centre as having said that it is ‘the first time since 1600 that the volcano has erupted’ (Surono, quoted on Reuters “Volcano erupts on Indonesia’s Sumatra after 400 years”, reuters.com).
The August 2010 Eruption of Mount Sinabung
Mount Sinabung is located in the north west of the island of Sumatra in Indonesia, around 40 miles south west of the city of Medan. The eruption itself began shortly after midnight, initially sending an ash plume around 5,000 feet into the air and generating lava flows (Reuters). Clouds of smoke and steam seen on the previous day had been attributed to rain (BBC, “Thousands flee Indonesia volcano on Sumatra”, bbc.co.uk).
Although some local newspaper reports indicated that one person had died as a result of the eruption, Sky News reported a government spokesman as saying that no deaths or injuries had been reported, although over 10,000 local residents had been evacuated form a four-mile exclusion zone (“Thousands flee homes after volcano erupts” by Adam Arnold, news.sky.com).
Volcanic activity appeared to decline in the immediate aftermath of the outburst of lava and some reports indicate that evacuees are already returning to their homes (BBC). Despite the apparent short-lived nature of the eruption, however, the volcano remained on a high alert throughout 29 August (Indahnesia website, “Changes in volcanic activity for Gunung Sinabung”, indahnesiacom).
The Eruptive History of Mount Sinabung
The 8,071 foot high Mount (or Gunung) Sinabung lies in an area which is characterised by high levels of tectonic activity, with regular large earthquakes (including the Boxing Day earthquake of 2004) and many volcanoes. The Global Volcanism Programme lists 37 volcanoes in Sumatra, four of which are currently under level 1 or 2 alerts (Indahnesia).
Having been inactive for so long, there is obviously limited information on the volcano's eruptive history. Although it is being widely reported that Mount Sinabung last erupted around 400 years ago (BBC, Sky, Reuters), the Global Volcanism Programme notes that ‘no historic eruptions have been recorded’, though it suggests that there may have been a previous eruption in 1881 (described as ‘uncertain’) with some observed activity in 1912 (Global Volcanism Programme, “Volcanic activity reports” volcano.si.edu).
Geological Context and Possible Future Eruptions
The high level of volcanic and earthquake activity in Sumatra is the result of its geological context. The island lies adjacent to the deep Java trench, where the tectonic plate which underlies the Indian Ocean descends beneath the Australian plate (California Institute of Technology, “Sumatran Plate Boundary Project”, tectonics.caltec.edu). At that boundary, the descending oceanic crust melts under pressure, generating magma which feed the volcanoes.
Because Mount Sinabung has been inactive for so long, it is very difficult to make predictions about its eruptive patterns. How long the eruption will continue and whether or not eruptions will be frequent from now on is even more difficult to predict than is the case for those volcanoes which erupt on a more regular basis.
Other volcanic eruptions, most notably that of Iceland's Eyjafjallajokull which took place earlier in 2010, have caused considerable disruption to human activity even where no causalties have been involved. In the immediate aftermath of the eruption of Mount Sinabung, however, it seems that the event is unlikely to cause major or long-term disruption.
