Fig. 5: Matched-field processing (MFP) of a DAS rock-fall seismogram.
From: Distributed acoustic sensing of microseismic sources and wave propagation in glaciated terrain
a 20 DAS channels filtered between 10 and 30 Hz. Notice the frequent occurrence of noise transients at amplitudes comparable to the rock-fall signal around 150 s. b Calculated back azimuth. c Calculated phase speed. d Normalized beam power showing a sudden increase of signal coherence within the DAS channels when the rock-fall signal is recorded. Color code represents normalized beam power and is the same as in panels (b) and (c). This shows that during the rockfall, the calculated back azimuths and phase velocities are stable, but jump between the grid search extremes at other times. During the rock-fall signal, back azimuth and phase velocity are consistent with Rayleigh waves emitted by visually observed rock impacts on the ground west of the instrumented site.
