Seismic noise monitoring of a maritime pine root-system failure during an overturn experiment

Key message Root-quakes occurring during the overturn of a maritime pine can be observed in situ using a seismic array, while estimations of epicenters of seismic events can help to locate the failure of the root-system over time. The mechanical response of maritime pine was investigated with a series of experiments performed in situ. During the overturning of four specimens, a seismic array was deployed at the ground surface to continuously monitor the micro-seismicity associated with the failure of their root-system. We identified seismic events during the traction process applied to each tree. A threshold force value and a significant duration of the traction process seem to be needed in order for cracks to occur, and for seismic events to be recorded. For all trees, we can identify tens of seismic events, especially during the most advanced stages of the experiments, prior to complete failure of the root-system. Using pairs of geophones and seismic intensity ratios, we can localize the epicenters of most of the events within the seismic network. According to the sensitivity of the array, all epicenters are roughly localized within a 1 square-meter area. The estimates of epicenters show that the events are approximately aligned to the direction of tension.