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Incorporating Laser Rangefinders into Lahar Detection Systems

Alexandra M. Iezzi1, Weston A. Thelen1, Emily Bryant1, and Craig Gabrielson1,2

  • Affiliations: 1U.S. Geological Survey, Volcano Science Center, Cascades Volcano Observatory, Vancouver, WA, U.S.A 2Geology Department, Western Washington University, Bellingham, WA, U.S.A. 

  • Presentation type: Talk

  • Presentation time: Tuesday 08:45 - 09:00, Room R280

  • Programme No: 3.15.5

  • Theme 3 > Session 15

Abstract

Mass movements such as lahars (volcanic debris flows) can occur at volcanoes with or without associated unrest and can be one of the most devastating hazards for life and infrastructure for tens of kilometers downstream. Detecting these events as early and robustly as possible is key to mitigating their effects. Systems installed around the world to monitor mass movements commonly use seismometers and infrasound arrays, along with other instruments such as webcams and tripwires. However, lahars have low-amplitude emergent onsets and moving source locations, making their initial detection and characterization with seismoacoustic methods difficult. Here we present results from multiple field tests of a laser rangefinder as a lahar monitoring tool, including successful recordings of small debris flows at an experimental flume and at Mount Rainier (Washington, USA). We find that while the laser rangefinder unambiguously detects these flows with high spatio-temporal precision, spurious recordings in the laser rangefinder data (noise) tend to correlate with high humidity and snow. Therefore, combining it with other multidisciplinary observations, such as seismic amplitudes, will be key in mitigating false detections, particularly during inclement weather. We discuss the capabilities of incorporating this into a real-time lahar detection system as a potential replacement for physical tripwires to provide confirmation of a lahar. These tests produced recordings that have allowed us to calibrate and evaluate lahar detection algorithms at Mount Rainier and served as a successful test for new geophysical equipment that may be useful for detection of lahars worldwide.