Is a volcanic eruption a hiccup or an explosion?

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Last December, a The top of La Soufrière, a volcano on the island of St. Vincent in the Caribbean, began to spew thick lava ooze. The fluid accumulation was slow at first; no one was threatened. Then at the end of March and early April, the volcano began to emit seismic waves related to the rapidly rising magma. Poisonous gas expelled violently from the top of the peak.

Fearing that the magma bomb was imminent, scientists sounded the alarm and the government ordered a complete evacuation from the northern part of the island on April 8. The next day, the volcano began to explode catastrophically. The evacuation came at the right time: at the time of writing, no one was killed.

At the same time, something similar but quite different is happening on the edge of the Arctic.

Since the end of 2019, more and more intense tectonic earthquakes have occurred under the Reykjanes Peninsula in Iceland, strongly suggesting that the underground world is opening up to make room for magma to rise. In early 2021, as an underground magma snake migrated around the peninsula, looking for an escape hatch to the surface, the ground itself began to change shape. Then in mid-March, the first of several cracks meandered through the earth roughly where the scientists expected, Spray lava into uninhabited valleys Named Gerdingdaru.

Here, locals immediately flocked to have picnics and selfies just a stone’s throw away from the lava flow. A concert was held there recently, and people used the ridge as an amphitheater.

In both cases, scientists not only accurately hinted that a new volcanic eruption is coming. They also predicted two very different forms that these eruptions will take. Although the “when” part of the equation is never easy to predict, the correctness of the “how” part is particularly challenging, especially in the context of the explosive eruption of La Soufrière. “This is a tricky question, they did it, they absolutely did it,” said Diana Roman, A volcanologist at the Carnegie Institute of Science.

Volcanologists have learned more and more about the conditions under which explosive eruptions may occur. For example, the presence or absence of groundwater is important, as are the gas content and consistency of magma itself. In a series of recent studies, researchers have shown how to read hidden signals-from seismic waves to satellite observations-so that they can better predict exactly how volcanic eruptions will develop: a loud noise or a whimper .

Something evil is coming

Like skyscrapers or cathedrals, the architectural design of Earth’s volcanoes is very different. You can see tall and steep volcanoes, ultra-wide and shallow volcanoes, and huge and open volcanic craters. Sometimes there is no volcano at all, but a series of small depressions or clusters of cracks, leaving scars on the earth like claw marks.

The lava flow from Geldingdalu volcano is relatively slow and predictable.

Photo: Anton Brink/Anadolu Agency/Getty Images

The prediction of volcanic eruptions raises many questions. The main one is: when? Essentially, this question is equivalent to asking when magma from below will travel upward through a pipe (the pipe between the magma and the surface opening) and break through with lava flow and ash, volcanic glass and bombs.

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