At the summit of Mt. Vesuvius is a vast crater, nearly 1,000 feet deep. Every month, a monitoring team carefully descends into this gaping hole to collect gas samples that could help determine how close the magma is to the surface.
Volcanologists Descend into Mt Vesuvius' Crater
Published: February 20, 2019
Narrator: At the summit of Mt Vesuvius is a vast crater, nearly 1,000 feet deep. Every month, a monitoring team carefully descends into this gaping hole to gather data. Today, geologist Chris Jackson is joining them.
Chris Jackson: Some of the critical bits of data about the volcano's behavior and the kind of threat it can pose, they can only be gotten from one particular location. So there's no choice about trying to collect it somewhere easy, you just have to go to a place that is relatively difficult to get to.
Narrator: Their mission is to collect vital gas samples. These could hold clues about how close the magma is to the surface. To get them, they need to climb down into the heart of Vesuvius’ massive crater. Their target is a fumarole — a gap in the rock where gases from the magma escape. The team takes samples to measure the levels of one these gases — carbon dioxide.
Jackson: What we are really interested in here are spikes in carbon dioxide coming out to the volcano, because that spike in carbon dioxide might mean that there’s new magma coming into the volcano, which could occur immediately before it erupts.
Narrator: Rising magma experiences less and less pressure, causing it to release more and more carbon dioxide.
Chris Jackson: The magma within a volcano is a little like the soda within this soda bottle. Both of them contain carbon dioxide, so CO2, dissolved within them.
Narrator: As the pressure drops… the gas comes out of solution…forming bubbles, which can escape to the surface.
Jackson: The reason the bubbles came out to the soda is because we released the pressure… And the same happens when magma rises up within a volcano. It is that decreasing pressure that allows the gas bubbles to expand and eventually come out the top of the volcano.
Narrator: Constant monitoring of carbon dioxide and earthquakes is vital to predicting when Vesuvius might erupt again.
The Next Pompeii
Produced and Directed by: Duncan Bulling
Digital Producer: Ana Aceves
© WGBH Educational Foundation 2019