The 2016 Kumamoto earthquakes in Japan led to Mount Aso erupting on 8 October, after 36 years of remaining dormant – exactly as a team of scientists had expected. They warn it may erupt again in a near future.
Mount Aso is one of the larges active volcanoes in the world, but for nearly four decades it hadn't posed a threat to the communities living in its vicinity. However, the earthquakes which struck the Kyushu region of Japan in April 2016 – with a 7.3 magnitude main shock – caused more than just damages to infrastructure and people.
It apparently led to the formation of new fractures in the vicinity of Mount Aso's magma chamber and volcanic cones, changing its spatial and mechanical properties and increasing the risk that it might erupt.
The study, published in the journal Science, was conducted by scientists from the University of Kyoto. In the immediate aftermath of the earthquakes, they got close to Mt Aso in the hope they would learn more about how faults and ruptures form nearby volcanoes.
Field work at the epicentre
The researchers conducted field surveys in the vicinity of Mt Aso a – they did a before-and-after comparison of fault distribution in the area following the quakes, collected seismic data, and analysed high-resolution Google earth images which suggested that new fractures and surface ruptures had formed.
"Our findings show that propagation of ruptures from this earthquake terminated in Aso caldera because of the presence of magma beneath the Aso volcanic cluster", lead author Aiming Lin said. These ruptures under the volcano's caldera are potential new channels for magma venting. As a result, spatial and mechanical properties of the Aso volcano are altered and this is thought to increase the risk of it erupting.
"The possibility that 2016 Kumamoto earthquakes could trigger a large eruption of Aso volcano in the near future, by the development of magma conduits in newly formed fractures, should be reassessed", the authors write in the research paper.
What are the odds?
The eruption on 8 October occurred on the day the study was accepted by the journal Science, thus confirming the scientists' findings in a very illustrative way. However, they believe this is just the beginning – other eruptions are to be expected.
Lin told IBTimes UK: "This is amazing event that we have warned about in our paper before the eruption, although we could not predict the accurate timing. The newly formed co-seismic ruptures under Aso caldera are potential new channels for magma venting, thus changing the spatial heterogeneity and mechanical property of Aso volcano. Therefore, I think it would erupt again".