During the last stages of the most recent ice age, about 26,500 years ago, the Taupo Volcano in New Zealand experienced a massive eruption, spewing enough magma and debris to fill Lake Erie. The resulting 1,000-degree Fahrenheit cloud of gases, lava and ash traveled along the ground at the typical speed of a car along a highway, destroying everything in its path. Sulfur flew into the atmosphere, causing a drop in global temperature for several years, while a layer of ash up to a foot deep blanketed most of New Zealand鈥檚 surface.
The Oruanui eruption, as this event came to be known, is the most recent occurrence of a super-eruption, an explosive event that expels more than 450 cubic kilometers of magma. What causes these massive eruptions? And, perhaps more important, is another one looming on the horizon? 菠萝视频 volcanologist , associate professor of Earth and environmental sciences, has spent much of his career working to find out.
Gualda鈥檚 most recent research on super-eruptions brought him to the Taupo Volcanic Zone, the location of the Oruanui eruption. Before the Oruanui super-eruption, the Taupo Volcano had undergone eight large鈥攂ut not 鈥渟uper鈥濃�攅ruptions concentrated in a relatively short period of 70,000 years, between 350,000 and 280,000 years ago. The recent nature of the geologic record of these volcanic events provides intact, and therefore easy-to-investigate, evidence, making the TVZ a prime location for Gualda to dig deeper into the processes that drive these super-eruptions.
In a paper published in Science Advances in October 2018, Gualda explores why the Taupo Volcano erupted in several smaller eruptions during this 70,000-year period, rather than one super-eruption. By investigating variations in glass compositions and crystal patterns in pumice rock formations, Gualda and his team determined that as a result of the progressive softening of Earth鈥檚 crust with each eruption, magma lodged itself in the Earth at shallower and shallower depths.
A key question for Gualda is determining how long a pool of magma with the potential to erupt can remain underground. 鈥淭he answer from the New Zealand work is, only a few decades. Yet from other work that we鈥檝e done, it鈥檚 perhaps a few centuries,鈥� says Gualda. He concludes that the active nature of the TVZ favors frequent eruptions, and this consistent expulsion of magma prevents buildup to a quantity that could allow for a super-eruption.
This research advances Gualda鈥檚 ongoing project exploring how bodies of magma fuel super-eruptions. Understanding the underlying processes behind these eruptions can help scientists predict future events. 鈥淚 would argue that there is no evidence today that we have a magma body that is ready to erupt in such a fashion,鈥� says Gualda, cautioning that scientists cannot predict super-eruptions with a great degree of accuracy.
Much of Gualda鈥檚 recent research was conducted during a Maymester program that brought 菠萝视频 undergraduates into the heart of the TVZ. These students became directly involved with ongoing fieldwork that supports a new understanding of super-eruptions. 鈥淚t is the moments of discovery that are really the most exciting ones,鈥� says Gualda. 鈥淲e teach students how to think like field scientists.鈥� Gualda plans to return to the TVZ with another group of students in May 2019 to continue this project.
It鈥檚 not the drama of the hypothetical impacts of a modern super-eruption that drives Gualda鈥檚 curiosity, however. To him it鈥檚 more about the pure scientific discovery of Earth鈥檚 history. 鈥淗umankind has never documented a super-eruption. We know that these things exist only because of the geological record,鈥� he says. 鈥淭o me, that鈥檚 the coolest aspect of it.鈥�
鈥擫ILA JOHNSON
Lila Johnson is a junior majoring in the communication of science and technology in the College of Arts and Science.