Q: How long could the effects of this latest eruption in Indonesia last?
A: It is hard to tell how long the eruption will last. This volcano has been erupting since December 2023 – so almost a year now.
However, it has only become more violently eruptive since the start of November and that is what is causing the problem – pushing large volumes of ash into the atmosphere and spreading them 800 km to the west, as far as Bali.
If the eruption continues, but is less intense, the ash cloud could disperse, or the air currents could move it in a different direction so that it no longer impacts flights.
So, there are many factors to consider – the eruption can continue for many months or years, but the impacts could vary.
Q: Why is Indonesia prone to such explosive volcanic eruptions?
A: Indonesia sits between a number of tectonic plates – mainly the Australian Plate to the south and the Philippines Sea Plate and Pacific Plate to the east, and many smaller plates besides.
Ocean crust is being pulled down beneath the edges of the Sunda plate on which most of Indonesia sits. Gasses and vapours liberated from that subducting material creates gas-rich magmas which then erupt explosively
Q: What makes a volcano erupt in such a violent way?
A: Similar to the above – the magmas in these types of volcano are very gas and vapour rich. As they rise, the gasses are released and if they can’t escape, pressure builds up until it erupts explosively, breaking up the surrounding rocks, creating the large volumes of ash – tiny fragments of rock.
Q: Does this eruption mean other volcanoes nearby are more likely to also erupt?
A: No – volcanos tend to behave independently of one another.
Q: Are there any other volcanoes expected to erupt soon which could impact air travel?
A: There are numerous volcanoes in Indonesia, in particular a string of them extending from Sumatra, through Java, Bali and Lombok to Flores, the location of Lewotobi.
Some are recently active while others like Lewotobi may become active after a period of dormancy.
Whether or not they will affect air travel is another matter – in many cases aircraft can travel around them. It is really only when an ash cloud extends over flight paths that can’t be changed – for example, on the approach to an airport, that flights will have to be cancelled.
Flights to Bali have been disrupted on a number of occasions in the recent past (last five to 10 years), but on those occasions due to the eruption of volcanoes much closer at hand – on Lombok and on the island of Bali itself.
Q: Can we predict such eruptions before they happen, or predict how long they will last?
A: We can monitor activity levels of volcanoes – emission of gasses for example, or small earthquakes caused by movement of magma below the surface, and that might be an indication that an eruption could occur.
Exactly when it might occur is much more difficult to say. And once the eruption has started, there is little that we can do other than to watch for signs of its intensity waning – but that may take weeks or months, even years.
Lewotobi’s current phase of activity began in December of last year, so it has been going for 11 months already.
