Acoustic and micro-seismic signal of rockfall on Matterhorn

Despite substantial technical advances in the instrumentation of steep rock slopes, our ability to detect precursor events of rock slope instability remains limited. In this study, we investigate the acoustic and micro-seismic signal of fracture and rockfall events at Matterhorn. A rockfall event with a volume of 2 to 3 m3 was recorded by crackmeter and micro-seismic measurements on 14 August 2015 UTC 20:10 with high energy concentration below 100 Hz. The acoustic emission (higher frequency range) did not capture the rockfall event itself, but occurs coincidently with preceding irreversible fracture displacements. In the lower frequency range, we clearly capture the rockfall event, but to our surprise the wave amplitude and energy during the rockfall event was not higher than in the preceding ten days.