Since mountains move at a geological pace, are geologists ever in much of a rush? Maybe that depends on the scientist. Out of the 1980 Mount St. Helens eruption, modern volcanology was born. Governments provided funding to develop forecasts for eruptions. Igneous petrology, the specialization focused on rock that began as molten lava, was about to come to a boil.
Big pockets of magma churn up close to a thin spot in the Earth’s crust, resulting in an occasional leak or blowout of lava and gases. Samples of igneous rock have tiny pockets of those gases, which can be examined through a variety of techniques, analyzed, and compared so that geoscientists can form models for forecasting hotspot activity.
In 2022, Berkeley’s Department of Earth & Planetary Science (EPS) welcomed an igneous petrology expert, Assistant Professor Penny Wieser. In her EPS 80 class, Wieser demystifies the processes in the Earth that shape our environment. “Everyone,” she warned, “should be aware of what is going on” under our feet. If current students aren’t aware that the Hayward fault runs right through Memorial Stadium, how can they be informed citizens?
Wieser’s future took shape when she saw the movie “Dante’s Peak,” starring Pierce Brosnan as a volcanologist. The possibility of “doing volcanoes as a job”? Wieser was off and running. She dove into the earth sciences major at Oxford and has barely paused for breath since. At Cambridge for graduate school, she kept up a fast pace. “Being on the university sailing team meant I was constantly taking time off my studies for fun stuff!”
EPS approached Wieser in 2020 with an invitation to apply, and she successfully competed with a pool of over 300 candidates. She spent the pandemic as a postdoc at the University of Oregon with Adam Kent, one of the new cadre of geologists using advanced imaging and analysis methods from chemical engineering to examine igneous rocks towards improving our understanding of volcanic systems.
The primary way to get a snapshot of the composition of a magma pocket has been melt inclusion studies. They are useful for analyzing trace elements and volatile components like water, carbon dioxide, and sulfur. Geoscientists can reconstruct the sequence of magmatic events, such as magma mixing, crystallization, and ascent. Melt inclusions yield insights, but they come with technical and interpretive challenges. Doing them is tricky, slow, and expensive. Wieser and others are turning to Raman spectroscopy of fluid inclusions instead. For many of these measurements, it is easier, faster, much cheaper, and gives comparable results.
Advances in Raman spectroscopy make it a favorite technique from electrical engineering to polymer chemistry and even forensic analysis and art conservation. It’s relatively simple to prepare samples, and the samples aren’t burned up by the testing. Chemical compounds have a signature or a fingerprint that can be detected even in samples that are as small as a single molecule. Professor Wieser is proving that, when applied to fluid inclusions, it gets results just as reliable as those of melt inclusion. “Raman spectroscopy measurements are robust and require only a fraction of the time and resources of melt inclusion studies,” she said.
So, volcanologists are closer to being able to forecast lava flows and volcanic eruptions. Eventually, civil authorities and residents will have enough time to respond wisely to emergencies. During the eruption of Kilauea in 2018, no lives were lost and the spots where magma rose were where the hazard maps predicted, but the size of the flow took geologists by surprise. It was the largest leak in two hundred years. Wieser’s research shows that Raman analyses of fluid inclusions from the eruption could have given nearly real-time information as solid as that from “postmortem” samples. The day may come when igneous petrologists like Wieser are more like volcano cardiologists than coroners.
Fluid inclusion slides are easier to prepare but still demand day after day of examining tiny bubbles in slices of lava. To find their chemical fingerprints she often polishes away her own. The data painstakingly gathered at the Raman microscope are wrung well and hung up to dry into reliable evidence. Imagine a day not long off when magma’s potential danger might not be tamed, exactly, but could be dealt with calmly, with foresight. Where to next? The Cascade Mountains, thanks to her recently awarded Heising-Simons Faculty Fellowship. Wieser will be applying her techniques to the highest threat volcanoes in that range, uncovering their history of past eruptions and discovering the warning signs of future hazards.