2023 has seen its fair share of volcanic eruptions, from the eruptions in Iceland to Krakatau in Indonesia. And 2022 was no different – with eruptions from the Lascar volcano in Chile, Mount Semeru in Indonesia, and Hunga Tonga in the South Pacific, as well as the quiet eruptions of Mauna Loa. 2022 was truly a year for volcanoes.
But how do scientists predict volcanic eruptions before they happen?
While eruptions like Mauna Loa are relatively calm and low-impact, eruptions like Mount Semeru and Hunga Tonga can cause devastating damage, forcing evacuations, destroying property, and even causing loss of life. Although it’s impossible to accurately predict the extent of damage caused by a volcanic eruption, there are ways to predict when they might occur.
What Causes a Volcano to Erupt?
A volcano erupts when magma rises to the surface due to lower density and pressure, aided by the formation of gas bubbles. The type and severity of an eruption depend on various geological factors, including the composition of the magma and the Earth’s tectonic activity. Here’s a breakdown of what causes a volcano to erupt:
Magma Formation
Magma is formed when the Earth’s mantle (the layer beneath the crust) melts. This melting can be caused by various factors, such as the movement of tectonic plates, the presence of hot spots, or the addition of water and other volatile substances that lower the melting point of rocks.
Pressure Buildup
As magma forms, it starts to rise towards the Earth’s surface because it is less dense than the surrounding solid rock. As it rises, the pressure decreases, allowing gasses dissolved in the magma (like water vapor, carbon dioxide, and sulfur dioxide) to form bubbles. This process is similar to the bubbles that form when you open a carbonated drink.
Eruption Trigger
The increasing pressure from these gas bubbles pushes the magma through the cracks and fissures in the Earth’s crust. When the pressure becomes too great for the crust to contain, it causes an eruption.
Types of Eruptions
The nature of the eruption can vary greatly depending on factors such as the viscosity of the magma (how thick or fluid it is), the amount and type of gases it contains, and the structure of the volcano itself. Magma with higher viscosity (like that found in stratovolcanoes) tends to produce more explosive eruptions, whereas more fluid magma (like that found in shield volcanoes) tends to create gentler, flowing lava eruptions.
Tectonic Activity
In regions where tectonic plates diverge or converge, magma can more easily rise to the surface, leading to frequent volcanic activity. For example, the Ring of Fire around the Pacific Ocean is a result of plate tectonics and is home to many of the world’s volcanoes.
Read More: The Origins of Plate Tectonics May Stretch Further Back in Earth’s History
