Extreme Rainfall Might Explain Volcanic Eruptions
Based on modelling experiments, researchers think this is more than just a hypothesis.
Rain and volcanic eruptions do not seem to be interconnected. But they may be.
In fact, just a few months ago, a study in Nature provided evidence that extreme rainfalls had triggered the eruption at Kīlauea Volcano in 2018.
Researchers came to this conclusion based on mathematical models. They computed the subsurface pressure built due to infiltration of water after the rainfall and right before the volcanic eruption.
What did researchers find in these simulations? They found that subsurface pressures were about 0.1 kPa to 1 kPa at depths between 1 km to 3 km. While these pressure levels might seem small, they are known to trigger ocean tides and earthquakes. And, because these levels were only observed at Kilauea Volcano after rainfall, the extreme rain periods were proposed as the cause of the eruption.
How does water infiltration increase chances of eruption? Let’s put it simply. As water infiltrates into the ground, it approaches the volcano’s magma reservoir. But the inner temperatures of more than 300 °C can quickly vaporize this water. As the water heats up it becomes vapour gas. Just like water boiling in a kettle. This water gas increases the pressure inside the kettle pushing against the wall and the lid. The lid tumbles because the vapour wants to escape. In the same way, the vapour increases the pressure in the rock pores, therefore, causing weaknesses in the ground. These fractures created in the volcanic subsurface ultimately can lead to eruption.
Is the hypothesis plausible?
Although the model seems to accurately support the connection between the two events, there is more evidence that further supports the link between extreme rainfall and volcanic eruptions.
First, according to the researchers, ground-based data showed no surface deformation before or after the volcanic eruption at Kilauea. This meant that underground movement of magma was not the cause. In this scenario, rainfall triggering is more likely.
Also, historical eruption records at Kilauea (1970 to 2018) showed a pretty consistent pattern of eruption during the wettest times of the year, including during rainy season. In fact, these eruption patterns have also been observed for other volcanoes. This evidence shows that volcanic eruptions occurring after heavy rainfall is more common than we think. Furthermore, data from the first quarter of 2018 showed that rainfall at Kilauea was indeed greater than average. With about 1.26 m in only 24 h! Breaking the nationwide record of downpour in all United States. And, a total of 2.26 m throughout the period before the eruption.
Lastly, researchers looked back at the past volcanic eruption at Kilauea in 1924 to further validate what they hypothesized. Rainfall data indicated that heavy rain also preceded the eruption and that many of the features after the event resembled the eruption style observed in 2018.
But.
Other researchers in the area remain skeptical. According to Michael Poland, a volcanologist at U.S. Geological Survey, ground-deformation data from the Hawaiian Volcano Observatory showed a significant subsurface ground inflation at Kilauea, hence contradicting the lack of ground deformation pointed out in the study published in Nature.
Regardless, this study not only seeks answers to volcanic eruptions, but it also points out a bigger problem: the extreme weather phenomena caused due to climate change.
Predicting volcanic eruptions amidst extreme weather
Climate change is real, and we have already been experiencing it in the last decades. These changes in Earth’s climate are reflected in extreme weather events such as heatwaves, drought, heavy downpour, flooding, and hurricanes. With intense rainfalls happening more often, the effects on Earth’s may be observed through volcanic eruptions.
In that case, paying close attention to rain forecast might be a future approach to predict volcanic eruptions. Or it might not?
