Figure S3b. Best-fit regression of decay in seismic power with
distance, and its frequency-depedency (equations [1a] and [1b]
in the main manuscript) based on active seismic surveys for each of the
24 seismic sensor locations. Each line is fitted through the average of
20 repeated sledgehammer impacts, (see also Figure 5d in the main
manuscript). The thicker the line, the greater the number of seismic
sensor locations that share the same \(K_{0}\) and \(\eta\) values (i.e.
Table S3), from a single seismic sensor location sharing the same
parameter values (i.e. thinner line), up to three seismic sensor
locations sharing the same parameter values (i.e. thicker line). Note
that seismic sensor locations presenting the same\(\ K_{0}\) and\(\eta\) values were estimated based on a single active seismic
experiment encompassing the location of the different sensors. The
parameters found by Bakker et al. (2020) for an alluvial channel (in
red), and proposed by Tsai et al. (2012) for a generic bedrock site (in
blue) are presented for comparative purpose.