When you hear stories about volcanoes spewing lava and ash, you may worry about the people nearby. In fact, about 1 in 10 people in the world live within 100 kilometers of the volcano that erupted. For people who live near volcanoes, farm on fertile land, or visit their interesting places, it is very important to understand the causes of the eruptions.
Why is the volcano erupting? How will the explosion end? When will it end?
Our new research has been published [5 July] in Advances in Science it uses laser technology to read into the composition of the magma that erupts over time.
Because the chemistry of magmas affects fluidity, eruption, and hazard potential, our work can help monitor and predict the evolution of volcanic eruptions.
Solving the chemistry of explosive meltdown
Magma – molten rock – is made up of water (called “melt”), gas, and crystals that grow as the magma’s temperature drops on its journey to the Earth.
When magma erupts into lava, it releases gas (containing water vapor, carbon dioxide, sulfur dioxide, and other chemicals) and cools to form igneous rock.
This stone consists of crystals that have cooled slowly inside the mountain, embedded in a shiny stone that is fixed on the surface.
As a result, mountain rocks can look like “stone” chocolate. The crystals formed in the bowels of the volcano are a perfect repository for the fossils that form before the eruption.
However, crystals can get in the way when we want to focus on the melt that takes them to the surface, and how the solvent properties vary throughout the eruption.
To isolate the melting signal, we used an ultraviolet laser, similar to that used in eye surgery, to blast the stone matrix between the large crystals.
We then analyzed the particles produced by the laser and mass spectrometry to determine the composition of the volcanic eruptions. This method allows rapid chemical analysis.
This provides a quick and detailed measurement of the chemistry of the melt and its evolution over time, compared to the traditional analysis of the whole, or the deep separation of matrix and crystal fragments from crushed rock samples.
Although we call these crystals “large”, they are often as small as a grain of salt (or even the size of a chicken if you’re lucky!) and are difficult to remove.
A devastating disaster in the Canary Islands
Our research focused on the 2021 eruption of La Palma, the most destructive volcanic eruption in history in the Canary Islands.
From September to December 2021, 160 million cubic meters of lava covered an area of more than 12 square kilometers. It destroyed more than 1,600 homes, forced the evacuation of more than 7,000 people, and cost more than €860 million (AUS$1.4 billion).
We analyzed lava samples systematically collected by colleagues in Spain throughout the three months of the eruption.
These are the most valuable samples as far as we know their exact date of eruption, and most of the sample sites are now covered by later lava from the eruption.
Using the laser method, we were able to see the changes in earthquakes and sulfur dioxide emissions, as well as volcanic eruptions and the dangers that follow.
This included a change from the thick, bulldozer-like lava at the beginning of the eruption, to the explosive lava that formed rapidly. lava flows and lava flows after the eruption.
We also found a significant change in the chemistry of the lava about two weeks before the eruption, which indicates the cooling of the magma due to the downward pressure of the magma.
Similar changes can be monitored as a sign of future wind explosions around the world.
Forecasting volcanic activity
We can’t stop volcanoes from erupting, and we can’t go inside them, as French novelist Jules Verne believed. But volcano monitoring has advanced significantly in recent decades to allow us to ‘look’ at volcanoes and better predict what will happen next.
Our project aims to provide a laboratory tool to test volcanic samples collected during future eruptions. Its purpose is to calculate the evolution of mountains, to understand why they start and when they will end.
With about 50 volcanoes erupting around the world at any given time, you’ll soon see another volcano erupting in the news. This time, you can think about the importance of volcanology to understand how volcanoes work and what causes them to erupt, protecting the people around them.
Correction: The original article stated that the 2021 eruption of La Palma produced 160 cubic meters of lava. The correct figure is 160 million cubic meters.
Teresa Ubide, Associate Professor – Igneous Petrology/Volcanology, The University of Queensland; Alice MacDonald, PhD Student, University of Queensland, and Jack Mulder, Lecturer, University of Adelaide
This article is reprinted from The Conversation under a Creative Commons license. Read the first article.