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Characterization of Environmental Seismic Signals in a Post-Wildfire Environment: Examples from the Museum Fire, AZ
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  • Porter Ryan C,
  • Joyal Taylor,
  • Rebecca Beers,
  • Ann Youberg,
  • Joseph Loverich,
  • Schenk Edward,
  • Peter R. Robichaud
Porter Ryan C
Northern Arizona University

Corresponding Author:[email protected]

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Joyal Taylor
Northern Arizona University
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Rebecca Beers
Arizona Geological Survey, University of Arizona
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Ann Youberg
Arizona Geological Survey
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Joseph Loverich
JE Fuller Hydrology and Geomorphology
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Schenk Edward
4Flagstaff Water Services, City of Flagstaff
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Peter R. Robichaud
USDA Forest Service
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Abstract

The 2019 Museum Fire burned in a mountainous region near the city of Flagstaff, AZ, USA. Due to the high risk of post-wildfire debris flows and flooding entering the city, we deployed a network of seismometers within the burn area and downstream drainages to examine the efficacy of seismic monitoring for post-fire flows. Seismic instruments were deployed during the 2019, 2020, and 2021 monsoon seasons following the fire and recorded several debris flow and flood events, as well as signals associated with rainfall, lighting and wind. Signal power, frequency content, and wave polarization were measured for multiple events and compared to rain gauge records and images recorded by cameras installed in the study area. We use these data to demonstrate the efficacy of seismic recordings to (1) detect and differentiate between different energy sources, (2) estimate the timing of lightning strikes, (3) calculate rainfall intensities, and (4) determine debris flow timing, size, velocity, and location. This work confirms the validity of theoretical models for interpreting seismic signals associated with debris flows and rainfall in post-wildfire settings and demonstrates the efficacy of seismic data for identifying and characterizing debris flows.