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Characterization of a Debris Flow at Mount Rainier via Seismoacoustics and a Novel Usage of a Laser Rangefinder

Description: 

Mass movements such as debris flows and lahars can occur at volcanoes with or without associated unrest and have the potential to impact life and infrastructure for tens of kilometers downstream with little warning. Many 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. Recordings from such events can be used to develop and test novel monitoring techniques as well as detection and characterization algorithms in the absence of larger, but less frequent, lahars.

Here we present recordings of a small debris flow at Mount Rainier (Washington, USA) that occurred on August 15, 2023, in the Tahoma Creek drainage. Mount Rainier has had at least 11 large lahars over the last 6,000 years, including one occurring without evidence of eruptive activity. In response to this hazard, the USGS and partner agencies operate the Rainier Lahar Detection System (RLDS) that was recently upgraded and densified. The current network consists of broadband seismometers, infrasound arrays, tripwires, and webcams concentrated along multiple potentially hazardous drainages. The 2023 debris flow was recorded by this network and by a suite of temporary campaign geophysical equipment. Among these instruments was a laser rangefinder recording at 1 Hz, co-located with a seismometer and infrasound sensor directly adjacent to the channel. The intent was to test its utility in detecting lahars as a potential replacement for tripwires currently in use to provide confirmation of a lahar. The laser rangefinder and co-located instruments clearly recorded the flow, in addition to the 10 broadband seismometers and 4 infrasound arrays in the permanent network, as the flow moved down the drainage. The 2023 debris flow produced recordings that have allowed us to calibrate and evaluate RLDS algorithms and served as a successful test for new geophysical equipment that may be useful for detection of lahars at Mount Rainier and elsewhere.

Session: Detecting, Characterizing and Monitoring Mass Movements - I

Type: Oral

Date: 5/2/2024

Presentation Time: 08:30 AM (local time)

Presenting Author: Alexandra

Student Presenter: No

Invited Presentation: 

Authors