Submarine volcanoes: do they represent a risk for Peru?

The massive eruption of the underwater volcano Hunga-Tonga-Hunga-Ha’apai, located near the island of Tonga, occurred more than 10,000 km away from the Peruvian coast. Even so, the anomalous waves generated by this event caused the death of two women in Lambayeque Y affected several coastal cities. It is inevitable to ask: what is the risk that submarine volcanoes represent for our country? To resolve that and more doubts, El Comercio spoke with Marco Rivera, a scientific researcher at the Geophysical Institute of Peru (PGI).

—Some media have indicated that last Saturday’s eruption in Tonga was the largest recorded in at least 30 years. Why has this event been so powerful?

On December 20, this underwater volcano was reactivated. Since that date, it has been generating ash explosions that reached up to five or seven kilometers high, according to reports. That’s quite a lot actually. But keep in mind that Tonga is a zone of weakness where the magma easily reaches the surface, which will produce quite explosive eruptions. But be careful, not all marine areas have this type of volcanic activity.

—That is to say, not all submarine volcanoes will be this violent…

Yes. Not far away, . However, this activity is characterized in that there are only lava flow emissions. These are relatively more passive, as is also the case in Hawaii. They are quite slow emissions of lava flows, and as they ascend, they are deposited on the seabed.

—Can a submarine volcano in areas of weakness, such as Tonga, represent a risk for the country?

This underwater volcano in Tonga generated tsunamis but in nearby areas. The coast of Peru is more than 10,000 kilometers away. The danger will depend a lot on the type of eruption. This eruption has not yet been analyzed, but I would imagine that it must have had a volcanic explosion index of between four and five, on a scale from 0 to 8. . The danger exists.

—The Pacific Ocean is home to many underwater volcanoes?

In the Pacific there are hundreds of submarine volcanoes. These, over time, will give rise to new islands. We have quite a bit of volcanism, which we observe year after year. For example, the Tonga volcano was active in 2014 and 2015. There is no active submarine volcanism near the Peruvian coast. . Although it is true that we did have this kind of volcanic activity millions of years ago, especially in the south of the country, now it no longer exists. Currently, our volcanism is concentrated along the Andes mountain range.

—Is the rate of explosion of submarine volcanoes greater than those located on the surface?

Yes, like the one in Toba or the one of Krakatoa. They are volcanoes that grew at the bottom of the sea. These have generated much more powerful and violent eruptions that have a volcanic explosion index of between 6 and 7. But we must not forget that there are also large eruptions on the continents. For example, .