An application to the Tonga volcano

Developing an algorithm to estimate the size of the volcanic eruption in less than an hour

This algorithm amounts to a "simple framework" for now and should be improved in the future as data is collected on more volcanic eruptions.

The eruption of the Tonga volcano in 2022 was officially named the largest volcanic eruption of the 21st century, according to the results of a study published on April 20 in the journal Geophysical Research Letters. The study showed that the Tonga eruption was similar to the largest volcanic eruption ever recorded.

After ejecting a substance with a volume of about 10 cubic kilometers, it generated an atmospheric shock wave that circled the globe several times. Producing an ash plume about half the size of France, the eruption of Tonga became equivalent in strength to the catastrophic 1991 eruption of Mount Pinatubo in the Philippines.

Recently, researchers Piero Poli and Nicolae M. Shapiro from the University of Grenoble Alpes in France developed an algorithm to determine the size of the Tonga eruption, which in turn helped greatly reduce the amount of field work and direct measurements required.

The researchers set the Volcanic Explosion Index (VEI) rating at 6, and predict a similar eruption every 50-100 years. It should be noted that the highest value of the volcanic eruption index is 8 that of eruptions that occur every 50,000 years or so, and these eruptions can produce ejecta with a volume of up to 1,000 cubic kilometers.

According to a report published in Science Alret, the eruption of the Hong Tonga-Hanga Hapai volcano, which occurred in January of this year, destroyed 90% of the uninhabited island of Hong Tonga Hapai, which appeared in 2015 after another eruption of less intensity than the Tonga volcano.

Experts believe that the way the volcano erupted directly into sea water rather than open air may have had something to do with the size of the subsequent eruption, and the strength and distance covered by the subsequent tsunami.

Algorithm based on seismic observations

Polley and Shapiro write in their paper that, "Despite an unprecedented wealth of high-quality scientific data that has become available relatively quickly, it is not possible to estimate the main quantitative parameters of the Hong Tonga eruption - such as measuring its size compared to previous major eruptions." - quickly using standard monitoring algorithms". "This underscores the need to develop new approaches to analyze this large amount of electronic data," they said.

So having an algorithm like this would be very useful, especially in the case of volcanic eruptions that occur in remote locations where there is not a lot of equipment around to measure the event directly.

In their innovative approach to calculating the size of a volcanic eruption, the two researchers rely on seismic waves that are captured at record speed by a vast network of hundreds of seismic monitoring stations. When sufficient data is available, the developed algorithm can estimate the size of the volcanic eruption in less than an hour, which can help assess the size of the resulting ash cloud and how this cloud affects the surrounding environment.

Polly and Shapiro say the algorithm amounts to a "simple framework" for now, and should be improved in the future as data is collected on more volcanic eruptions.

Source : Science Alert