A collaborative team of researchers led by Gadja Mata University has analysed summit dome instabilities at Merapi Volcano, Indonesia, in order to learn more about what causes volcanos to collapse.
Why are scientists studying the process of volcanos collapsing?
Lava domes form at the top of many volcanoes when viscous lava erupts, and when they become unstable, they can collapse and cause a hazard. The researchers’ intention is that by understanding the inner processes, volcano collapses can be better forecasted.
Catastrophic volcano collapses and associated explosions, such as the collapse of Mt St Helens in 1980, are widely considered as unpredictable. This is because the physical properties, stress conditions, internal structure of volcanoes, and the lava domes on top of many volcanoes are not well understood and can adjust precipitously from one day to another.
This collaborative study, led by Gadja Mata University in Yogyakarta Indonesia, includes researchers from Uppsala University in Sweden, and from the German Research Centre GFZ at Potsdam. This scientific collaboration means that researchers can now explain summit dome instabilities and associated pyroclastic flows at Merapi volcano, Indonesia.
The study combines novel drone-based photogrammetry surveillance over several years with mineralogical, geochemical, and mechanical rock strength measurements.
What has this study revealed?
This research has demonstrated that a horseshoe-shaped fracture zone in the volcanoes summit region that formed in 2012, and which guided intense gas emission in the past, was subsequently buried by renewed lava outpourings in 2018.
The new lava dome that has been forming since 2018 started to show signs of instability in 2019, and the researchers were able to display that the summit dome of the volcano is currently collapsing along this now-hidden fracture zone.
Scientists then considered the changes that must have occurred along this now buried fracture zone from long term gas flux, by measuring the composition and physical properties along similar fracture zones in the volcano’s summit region. They concluded that weakened rocks of the hidden fracture zone are likely the main cause for the location of the ongoing summit instabilities at Merapi.
This discovery now provides an opportunity for monitoring teams to be introduced at volcanoes, that can better forecast locations of potential volcano collapse, by employing long-term remote sensing monitoring techniques to assess the hazards associated with summit dome, and edifice failure and collapses at active volcanoes worldwide.