Characteristics of seismic and acoustic signals of rock falls: an experimental study

Seismic and acoustic signals induced by rock falls and rock avalanches always contain abundant information about movement processes. By simultaneously monitoring and analyzing the characteristics of the two physical signals, there is a better opportunity to closely interpret the behaviors of the processes closely. This study conducted small-scale rock fall field tests on a creek bank. Three types of field tests including single large rock fall, single small rock fall, and rock-mixture fall tests were carried out. Low cost and easy-to-install accelerometers and microphones were used to record both seismic and acoustic signals, respectively. The results affirm that the characteristics of the seismic and acoustic signals are generally similar and correlated due to the signals being caused by the same event energy sources. The attenuation of acoustic signals was less than that of seismic signals and high-frequency portion of the seismic signals attenuates quickly in stratum. It was also shown how the surface wave velocity of the stratum of the test site was estimated. In addition, the larger the rock mass, the lower the seismic frequency was found to be. The possible practical significance of this study is provided, and the simultaneous use of acoustic and seismic signal monitoring to rock falls/landslides is promoted.