During an unusually dry monsoon season, a fire ignited in the Dry Lake Hills located north Flagstaff, AZ on July 21st, 2019. The Museum Fire grew to 1,961 acres before containment in early August. The combination of a recent major wildfire and the onset of seasonal monsoons make the burn area a location where debris flows and flooding are likely over the next few years. In order to better understand debris flow initiation and characterize their downslope travel, we deployed a small network seismometers to record seismic signals associated these events. Seismic data collected by this array are being compared to other observations including pre- and post-event surface DEMs of scoured channels, rain gauge data, and mapping of downstream debris flow deposits. This will allow us to calibrate seismic observations to estimates of debris flow volume, grain size, and velocity and expand upon previous efforts to assess debris flows using geophysical data. The broad objectives of this effort are 1) to use seismic signals to characterize debris flows events as they travel downslope and 2) to determine the effectiveness of deploying a seismic monitoring network to serve as an early warning system for debris flows in the future. The data collected by the seismic array are publicly available from the IRIS DMC and a map showing the station locations is available here.

Codes for analyzing and/or visualizing the data will be made available upon request.

Major rain events recorded thus far occurred on the following dates:
8/28/2019
8/29/2019
09/23/2019

This work is funded by the National Science Foundation and the US Forest Service. Field support and instrumentation were provided by by IRIS PASSCAL.

Seismic record of a debris flow on August 28, 2019. Top: Seismic recording of event. Yellow lines are nearby lightning strikes, blue lines are rain data (intensity and cumulative rainfall), black is ground velocity in m/s. Middle: Seismic signal power. Bottom: Power spectral density plot of debris flows.