The Cordón Caulle volcano in Chile is part of the Puyehue-Cordón Caulle Volcanic Complex along the Andes mountain range in southern Chile. Philipp Ruprecht, an associate professor at the ΒιΆΉΣ³» in the Department of Geological Sciences and Engineering, recently received funding to continue studying the volcanism of Cordón Caulle. Funding from the Frontier Research in Earth Sciences grant from the National Science Foundation totals $2.5 million to better understand how the volcano is changing and what risks might arise in the region.
Cordón Caulle erupted in 2011. This was a big deal for volcanologists like Ruprecht, because this volcano is one of only two which has produced a rhyolitic eruption documented with modern scientific methods. Rhyolitic eruptions contain a lot of silica, which makes them very explosive while often finishing with uniquely thick lava flows. When Cordón Caulle erupted, it did something strange: it erupted explosively, sending ash and pumice high into the air, similar to the Mount St. Helens eruption in 1980, and effusively, pouring out viscous lavas in the form of thick slow-moving rock-like walls, at the same time.
During that rarely witnessed eruptive episode the landscape changed quickly as magma also intruded just a few hundred feet beneath the surface layer. This is known to geologists as a laccolith, and the laccolith at Cordón Caulle moved the landscape up by more than 500 feet. Since then, the entire region continues to move upward about one inch per month, even more than ten years after the eruption, likely due to new magma having refilled the main magma chamber. That may not seem like much, but in the geophysical world, that is a very high rate of change. With abundant rain or snow in this part of Chile during the winter months, a vigorous hydrothermal system has established itself. Near the laccolith, this water flows into the cracks in the surface, warms up, and resurfaces in the lower lying rivers at temperatures as high as 120 degrees Fahrenheit.
The Chilean Andes are home to the world’s largest-magnitude earthquake ever recorded, a 9.5 magnitude earthquake which struck in 1960 about 100 miles to the west of Cordón Caulle near the town of Valdivia. Just two days later, Cordón Caulle erupted in a similar eruption to the 2011 one. Such large earthquakes are often associated with additional geohazards like tsunamis and landslides. Hydrothermal systems often initiate mineral reactions that could introduce clay in the landscape, which allows surface materials to slide more easily and further, increasing the risks of landslides.
Cordón Caulle is a great place to study the interconnectedness of geohazards, Ruprecht said, because all these hazards come into play in the volcanic complex, which itself is the result of a subduction zone that formed the Andes starting more than 100 million years ago.
Ruprecht and his colleagues will continue to build on years of collaborations with Chilean volcanologists and geologists, including several that have resulted in research publications. There are seven principal investigators on the research project, including Ruprecht’s colleague in the Department of Geological Sciences and Engineering, Joel Scheingross, who visited Chile early this year. Ruprecht said Scheingross, an associate professor who studies geomorphology, was struck by how quickly the landscape is changing.
“I don’t want to be alarmist,” Ruprecht emphasized. “We want to understand the physical mechanisms, and if we understand them better, we can be useful locally.”
Cordón Caulle provides unique access to a shallow magma body. While most magma bodies are three or four kilometers below the surface, Cordón Caulle’s is just 200 meters below the surface, under the laccolith. While this is unusual and not as common in other systems, it will still help the researchers answer questions about magma bodies.
The grant funding will provide the researchers the ability to perform a slew of analyses. During a visit earlier this year, researchers continued collecting data related to the material released by the volcano using chemical analyses, installation of geophysical monitoring systems, gas measurements, temperature measurements and drone surveys. While back at home in the lab, they continue to learn about its landscape changes through satellite-based monitoring.
The drone surveys done earlier this year were supported by the Center for Transformative Environmental Monitoring Programs (CTEMPs) lab at Oregon State University and the ΒιΆΉΣ³». Chris Kratt, CTEMPs Laboratory Coordinator at the ΒιΆΉΣ³», went to Cordón Caulle with two students, Kayleigh Dohm and Odezsa Gautschi, who both operated the drone. The drone survey uses a magnetometer, which measures magnetism, suspended from the base of the drone. Measuring magnetism can give the researchers an idea of how large the magma body is. Unfortunately, due to a lack of access to updated data about the height of the laccolith, some of the equipment was damaged. Student researchers from another drone lab at the University, Faith Machuca and Hannah Potts, will be joining the field team in Chile this winter to resurvey the volcano with the drone and magnetometer.
Scheingross’s lab will contribute to the project by investigating the geomorphology and landscape evolution of Cordón Caulle and modeling erosive processes. He is currently recruiting a graduate student that will join the team during future trips to the Andes.
Ruprecht’s lab will support the project by conducting near-vent volcanological and geochemical analyses, helping to understand the chemical processes taking place in the volcano. A postdoctoral researcher soon to be added to the team will work specifically to understand why some magma was intruded near the surface instead of erupting with the rest of the magma. Undergraduate Audrey Topp, a recent recipient of the Mackay Outstanding Undergraduate award, worked for two years in Ruprecht’s lab to describe deformation that the lava flows caused in the landscape.
Seismic data collected during and since the 2011 eruption are being analyzed as well to better understand the relationship between the laccolith development and the concurrent seismic activity.
All these analyses will help inform the chronology of the volcanic activity and will help the researchers understand what happened in the past, what is happening now and what can happen in the future. Ruprecht and his colleagues will work closely with those in Chile to develop a clear picture of the volcano and the geohazards associated with it.
Lassen Volcanic Center has a similar structure to Cordón Caulle, with an active hydrothermal system, relatively recent eruptions and potentially similar compositions, which makes it a great analog to study in the U.S. Part of the grant will include funding to bring students from the Andes to the U.S. to study Lassen and Medicine Lake volcanoes. They will also visit the ΒιΆΉΣ³» at Lake Tahoe campus for a synthesis meeting.
The funding also supports the establishment of a field school which will provide graduate students with knowledge about geologic techniques and training for conducting fieldwork in remote and sometimes harsh environments. Additionally, the researchers have visited classrooms in the past in Neltume, a town in Chile which received large quantities of ash after the 2011 eruption of Cordón Caulle. Ruprecht and his colleagues will continue to visit and host field activities for seventh graders in Neltume for the duration of the project.
This project has developed into a large scientific network with more than 25 regular participants where US-based and Chilean students and scientists have created a mutually beneficial multi-disciplinary collaboration. Over the next five years this collaboration will significantly grow even further. There are six American universities or organizations involved in the project: the ΒιΆΉΣ³», Cornell University, the University of Oregon, Rice University, University of Wyoming, and the EarthScope Consortium. Chilean collaborating institutions include the Universidad de Chile, the Servicio Nacional de Geología y Minería, the Universidad Austral de Chile, the Universidad de Concepción, and Observatorio Vulcanológico de los Andes del Sur. All of the institutions will participate in the next field season in January 2025 when new instruments will be deployed and some of the first continuous year-long monitoring data will be retrieved.
