A distributed acoustic sensing and geophone array to study the Mt. Meager Volcano

Mount Meager volcano is part of the Garibaldi Volcanic Belt in western British Columbia, Canada and located 150 km north of Vancouver and 60 km from the community of Pemberton. The Mt. Meager massif is a highly active site for landslides causing a significant hazard. Notably, a 2010 landslide released 53 million m³ of material from the south face of Mt. Meager, which partially blocked the Lillooet River. Since then, satellite-based radar monitoring has measured displacement on unstable slopes of >27 degrees inclination throughout the massif. To investigate processes related to slope movement and landslides, including feedbacks between volcanic, glacier and earthquake dynamics, we deployed a novel and extensive seismic array across Mt. Meager. The field deployment includes several focused arrays. In particular, a slope near the location of the 2010 landslide is instrumented with distributed acoustic sensing (DAS) and several geophones along a 1-km line. The DAS site is located 2100 m above sea level on a ridge between a south-facing slope that exhibits movement and a north-facing slope that is covered with glacier ice. The DAS installation comprises an interrogator and a 3-km fiberoptic cable installed on both sediment and ice surfaces. The DAS fiberoptic cable includes 600 seismic sensors and spans 200 vertical meters. The ice portion of the cable includes several 10-m boreholes where the cable is looped into the ice. This study considers the experiment design and initial spectral data analysis of the geophone and DAS data with respect to slope movement below the dense-array site.