In 2018, Kilauea had its largest eruption in centuries. Because the volcano, which is located on the big island of Hawai’i, is easily accessible, it’s closely monitored by scientists. During this massive volcanic eruption, scientists from NASA’s Jet Propulsion Laboratory (JPL) were able to collect data on what was occurring. They discovered that this eruption was so much larger than usual because of a particular seismic event. According to a new study published in Nature, the collapse of Kilauea’s caldera likely occurred because of the volcano’s vents.
Understanding Caldera Collapse
When a volcano eruption occurs, sometimes a large depression, known as a caldera, will form. According to National Geographic, this happens because the magma inside the volcano provides support to the sides. After a volcano erupts, the magma chamber empties, eliminating that support. The sides of the volcano can collapse inward, forming a caldera. This can happen in an instant, with a violent eruption, or more slowly, as is the case with the caldera in the Kilauea volcano on Hawai’i.
When scientists Alberto Roman and Paul Lundgren at NASA’s Jet Propulsion Laboratory looked at the data coming out of Kilauea’s massive 2018 eruption, they wanted to know why it was the volcano’s largest in over 200 years. They were also interested in what specific mechanisms caused it. The answer to the first question was relatively easy — the volcano eruption was so large due to caldera collapse. As the caldera fell into the volcano, the large block of rocks became stuck inside the volcano, building the pressure inside.
According to Scientific American, during the 2018 volcano eruption at Kilauea, scientists were directly able to connect increases in lava flow from the building pressure to the eventual collapse of the caldera. The effects were seen within minutes of collapse up to 40 kilometers away from the volcano, and the “pressure pulses” created surges in lava flow that lasted for hours.
What Triggers Caldera Collapse?
The more difficult question, though, is what actually are the mechanisms that trigger the collapse of the caldera? According to a study published in Science, the Kilauea caldera collapsed after a very “small fraction” of the magma within the volcano was evacuated. This means that volcanoes don’t need the magma chamber to be anywhere close to empty before calderas collapse.
How, then, can we evaluate the mechanisms of what conditions lead to caldera collapse? It’s an important question because it will allow scientists to better predict how forceful a volcanic eruption will be. It can also assist in better understanding the levels of lava flow and how large the rift zone — which are the weak points of the volcano through which lava can erupt — will be. Understanding the mechanisms of caldera collapse will help scientists understand the short-, medium- and long-term effects of volcano eruptions, especially in populated areas around the volcano.
Kilauea is a shield volcano, which means that it is large, gently sloping and forms the shape of a shield. According to the U.S. Geological Survey, these volcanoes not only erupt at the summit, but they can also erupt in multiple of the aforementioned rift zones that radiate out from the summit and join together as they flow outward. The scientists at NASA’s JPL were able to put together a model of collapse based on the data from the 2018 eruption. They found that these rift zone vents, which are openings within the volcano’s structure further down from the caldera, were the culprit.
As lava flowed through these vents, the magma was released. The caldera collapsed after it lost this support structure during the volcano eruption. The rock falling into the magma chamber subsequently pressurized the lava flow, creating pressure pulses that increased the severity of the eruption.
Knowing what triggers the collapse of a volcano’s caldera is crucial, especially in heavily populated regions such as the area around Kilauea on Hawai’i.
“If we see an eruption at a low-elevation vent, that is a red flag or warning that caldera collapse is possible,” said Alberto Roman in the NASA release. “Similarly, if we detect earthquakes consistent with the slipping of the caldera rock block, we now know that the eruption will likely be much larger than usual.”
If scientists can predict the severity of an eruption, that means they can let officials know if evacuations are needed — helping local populations prepare and potentially saving lives.
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