What happens before a volcano erupts?
Accurately predicting when a volcano will erupt is an imperfect science.
Scientists look at the history of a volcano’s eruption, detect earthquakes through seismometry, and monitor ground deformation and changes in gas emissions to predict when an eruption is imminent. According to the Smithsonian Institution’s Global Volcanism Program, earthquakes and tremors almost always occur before a volcano erupts.
After thousands of earthquakes, officials in Iceland are warning that an eruption from the Reykjanes volcanic system is imminent, but exactly when it will happen is unknown.
the Icelandic Meteorological Office It uses data from measurements taken at the dam in Grindavík to run models and determine when and where magma might emerge.
4 classic types of volcanoes
However, the USGS notes that a volcano can show some, if not all, of these signs for an extended period without actively erupting.
“These precursors do not indicate the type or size of the eruption to expect (this information is best obtained by mapping previous eruptions),” according to the USGS. “Precursors can persist for weeks, months or even years before volcanic activity begins, or they can subside at any time and not be followed by an eruption. The Campi Flegrei volcano in Italy has shown signs of unrest for more than 60 years.”
Campi Flegrei volcano last erupted nearly 500 years ago. The volcano has been “turbulent” for more than 70 years, and tens of thousands of small earthquakes have occurred, along with the uplift of the ground in Pozzuoli, Italy, which has led to the expansion of the volcano’s crust. However, there was no active eruption with all the activity.
Geologists from University College London and Italy’s National Research Institute for Geophysics and Volcanology recently published a modeling study Earthquake Activity and uplift of the land to show that Campi Flegrei is “stretched almost to the breaking point” and could explode.
However, geologists cannot accurately predict when a volcano will erupt.
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Experts also say that looking at a volcano’s history alone is not the best way to predict when an eruption will start or end because volcanoes have been around for tens of thousands of years before we effectively monitored volcanic behavior.
some Volcanoes They erupt for months, years, or a full century, in the case of the Santa Maria volcano in Guatemala.
According to Volcanoes of the World, 93% of volcanic eruptions end within three years, 53% end within two months, and 24% end within one week.