Earthquakes with a chance of… volcanoes?
By Eloise Matthews
Fortunately, volcanoes are well-studied and there are a multitude of warning signs which enable this forecasting. One sign is the detection of shallow, low magnitude earthquakes, which are triggered by the ascent of magma, semi-molten rock which rises as it is less dense than the surrounding solid rock. Experiencing blockages on its way up causes pressure to build up, which fractures the overlying rock. These earthquakes are early warning signs – the eruption of Mount St Helens in May 1980, for example, was foreshadowed by seismic activity from mid-March of that year. The level of activity may increase sharply just before an eruption, but, like with Mount St Helens, this is not always the case.
The release of gases acts as both a warning sign and an effect of volcanic eruptions. Their release can indicate an eruption is soon to follow; however, the contents of the gases should be closely monitored because many active volcanoes steadily release gases even when not close to erupting. Changes in composition can be indicative of an impending eruption. For example, just two weeks before Mount Pinatubo in the Philippines erupted in June 1991, the sulphur dioxide content in the emitted gases increased roughly tenfold.
Overall, monitoring and forecasting techniques such as those discussed in this article should increase in use worldwide as societies develop and acquire suitable technologies, such as those for obtaining data on magma chamber stress to be passed through a Kalman filter. Despite physical settlements only being able to survive the effects of eruptions to a certain extent, improved monitoring and understanding will mean many more lives can be saved, enabling the human race’s further coexistence alongside these irrepressible forces of nature.