Saturday, 1 March 2014

An Australian and Indonesian Geological Relationship

Australia got its most recent reminder about the power of volcanoes only a couple of weeks ago. Mount Kelud (or Kelut) erupted on the populous island of Java in the Indonesian Archipelago. The resulting ash cloud has caused immense problems for people travelling to Asia or even Europe. The Darwin Volcanic Ash Advisory Centre (Darwin VAAC) advised that aircraft travelling on many of the popular Indonesian (particularly Bali), South and East Asian routes, would be in great danger of having engines failing. Therefore many flights were grounded.

The Darwin VAAC is responsible for Volcanic Ash advice covering the Indian sub-continent and South East Asia (The most concentrated number of active volcanoes in the world). Very few people realise the essential role that Australia plays in understanding the way volcanic ash behaves in such an active region. This is despite Australia has only a few isolated or insignificant volcanoes itself. Like the role of the VAAC, Australians don’t realise just how significant volcanism is to our second nearest neighbour (or indeed our nearest one, Papua New Guinea).

Readers of my blog will be aware that I focus almost entirely on the geology of the Northern Rivers, Eastern New England Tablelands and Mid North Coast areas of the state. Regular readers will also be aware that on occasion I indulge myself with a discussion or some opinions on geological matters elsewhere. Indonesia is just too important from a geological perspective to ignore. Having Indonesia come to our attention only when immigrants on boats are reported, volcanoes affect plane flights to Bali or the name Chapelle Corby is mentioned misses how much we are involved in and how much more we should be involved in managing volcanic hazards in our region. Including supporting Indonesia in its efforts to keep people safe.

Here are some selected facts about dangerous volcanoes:
  • Volcanic eruptions can be compared by a logarithmic scale called the Volcanic Explosive Index (VEI). 
  • VEI 0 are small explosive eruptions, VEI 8 are huge catastrophic eruptions. 
  • All recorded eruptions of VEI 6 or greater has killed someone. 
  • Approximately 50% of recorded eruptions of VEI 4-5 have killed someone. 
  • The majority of deadly volcanoes (VEI 6 or less) claim about 80% of their victims between 7 and 10 kilometers from the eruption. 
  • Lava causes only 0.34%-0.79% of deaths from eruptions. 
  • Pyroclastic flows cause between 33-46% of deaths from eruptions. 
Here are some selected facts about Indonesian volcanoes:
  • Monitoring the effect of volcanic ash in Indonesia is the responsibility of the Australian Bureau of Meteorology (via the Darwin VAAC). 
  • On average for every volcano that erupts in Indonesia, 27 people will die.
  • Five volcanoes have has significant (and recurring) eruptions already this year (Jan-Feb 2014). Those are Sinabung, Saiu Island, Kukano, Raung and Kelut. 
  • The largest explosive eruption known occurred at Toba about 30 000 years ago. 
  • In 1815 Mount Tambora erupted killing approximately 60 000 people and led to the “year without a summer” in Europe. 
  • In 1883 Krakatoa erupted with the resulting in approximately 36 000 deaths, the sound of the eruption was reportedly heard in many parts of Australia. 
  • Approximately 76 different volcanoes have erupted in Indonesia in the last ~500 years. Most of these erupting frequently. 
Here is an example of what people are trying to do about the dangers of volcanoes in Indonesia: This is a geology related conference that people in Australia probably never hear about.

More information on the Darwin VAAC can be found here.

*Auker, M. R., Sparks, R.S.J., Siebert, L., Crosweller, H.S. & Ewart, J. 2013. A statistical analysis of the global historical fatalities record. Journal of Applied Volcanology 2:2
*Smithsonian Institution. Smithsonian Institution / USGS Weekly Volcanic Activity Reports (All editions January-February 2014)


  1. Japan is another country which has many volcanoes, all be it, not quite as active as Japan. (Have been to see a few). Here we have lots more earthquakes. The first few times are bit of a novelty but after a while you wonder if it is the next big one happening. The land around here is rising but to the north it is sinking. After the big northern Japan earthquake quite a big of land was lost due to sea water entering the water table and saltification.

    1. Hi Paul,

      Japan is certainly an interesting country when it comes to volcanoes. Like Indonesia the volcanoes (and earthquakes) are directly associated with the subduction of a crustal plate under another one. The angle of the subducting plate near Japan seems to affect the chemistry of the magma differently to that of Indonesia. This seems to make the style of eruptions in Japan a little less violent than those in Indonesia.

      Having said that, with several volcanoes erupting a couple of times a year in Japan and your dense population - the danger is obvious!

      I'd love to get there and have a look one day.

  2. Hi Rod,
    I keep an eye on volcanic news at this site:
    Dangerous place in Indonesia, but good soil.

    1. Hi Dylan,

      In the list of blogs on the right hand side there is listed John Seach's volcano live site. It is very good but even better is the Smithsonian Weekly report. The Smithsonian report is more comprehensive but only comes out every 7 days.

    2. I sould have known and should have looked, thanks Rod I'll bookmark the other site.