EAPSI: Identifying Unstable Volcanic Slopes with Satellite and Geologic Data

Schleiffarth William K, Flagstaff AZ

Investigators

Abstract

Volcanic slopes are often steep, unstable, and prone to collapse, especially when groundwater interacts and weakens rocks within the volcanic edifice. A recent example of slope failure, which transformed into a fast-moving volcanic debris flow, occurred without warning on the flanks of Te Maari volcano on the North Island of New Zealand in 2012. Modern satellite imagery of the volcano suggests the slopes are weak due to the circulation of hot groundwater. The project will investigate the geology of the slopes to test the accuracy of satellite data interpretations. By completing detailed geochemical analyses of samples collected from the targeted slopes, the researcher will be able to determine to what extent these volcanic slopes are unstable and unsafe. This research will be conducted in collaboration with Dr. Ben Kennedy, a noted expert of volcanic processes, at the University of Canterbury in Christchurch, New Zealand. The results will not only aid in understanding the 2012 Te Maari slope failure but will provide important information about the accuracy of satellite data on unstable volcanic slopes, which can be applied worldwide. Both LIDAR data and field studies indicate that hydrothermally altered clasts are present in the debris flow deposit. Additionally, hyperspectral data now reveals ongoing alteration of the volcano, and provides a unique opportunity to study and sample these volcanic flanks. With these samples and hyperspectral and LIDAR data, the researcher will accomplish the following objectives: (1) determine the amount and style of hydrothermal alteration from the slopes that failed and produced the 2012 Te Maari debris avalanche using modern geochemistry techniques; (2) interpret remote sensing data to test whether it can accurately identify composition and textures at Te Maari; (3) apply remote sensing techniques to other volcanoes in the region to assess slope failure hazards. The results of this research will provide a framework to identify and classify hydrothermal alteration on other steep volcanic slopes, where high-resolution remote sensing data is available. In addition to a new framework for how to identify unstable slopes on steep volcanoes with satellite data, this work will improve hazard assessment and mitigation efforts. This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Royal Society of New Zealand.