5-1 Unraveling the details of the 2023 Tahoma Creek debris flow with multidisciplinary observations

Session: Advances in Mountain Hydrology: Connecting Cryosphere, Surface, and Subsurface Processes

Presenting Author:

Scott Beason

Authors:

Beason, Scott R¹, Iezzi, Alexandra M², Allstadt, Kate E³, Biegel, Katie M⁴, Collins, Elaine A⁵, Conner, Avery⁶, Thelen, Weston A.⁷, Thomas, Amanda⁸, Todd, Claire E.⁹

Abstract:

Mass movements, like debris flows and lahars, can occur at volcanoes with or without associated unrest and have the potential to impact life and infrastructure to tens of kilometers downstream with little warning. Seismoacoustic monitoring has been adapted for lahar early warning systems since the 1990s. However, fundamental challenges remain in terms of quantitative flow characterization, transferability of methods to new locations, and the ability to monitor multiple drainages simultaneously. The seismoacoustic signals generated by mass movements typically have low-amplitude emergent onsets and moving source locations, making their initial detection and characterization difficult. Small debris flows can occur at volcanoes due to heavy rainfall or snow- and ice-melt in the summer. Seismoacoustic recordings from small events can be used to develop and test novel monitoring techniques and detection and characterization algorithms in the absence of large, but less frequent, lahars.

Here we present recordings of a small debris flow at Mount Rainier, Washington, that occurred on August 15, 2023, in the Tahoma Creek drainage. The debris flow was recorded by a permanent monitoring network, including 10 broadband seismometers and 4 infrasound arrays. Given the frequency of debris flows in this drainage, we deployed an additional suite of campaign equipment that recorded this event, including seismic nodes placed along the channel and in small-aperture arrays nearby, a laser rangefinder to observe flow stage, and a time-lapse camera recording the glacier front where the flow originated. Within an hour of the flow occurring, a helicopter overflight captured post-flow observations and photos, which were analyzed in conjunction with high-resolution satellite imagery. We combine these multidisciplinary observations to estimate flow volume, extent, and velocity, compare arrival time estimates from different datasets, investigate flow pulses through time, and determine the transition from debris flow to hyperconcentrated flow that occurred. We utilize dense, temporary, multidisciplinary observations to enhance our understanding and characterization of the flow, with a particular focus on how it was recorded on the permanent monitoring network, and assess existing limitations in the capabilities of the permanent monitoring network to characterize flow properties. Recordings of the 2023 debris flow allow us to calibrate and evaluate lahar monitoring algorithms at Mount Rainier, which may be extended elsewhere.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7438

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