Towards the monitoring of underground caves using geomatics and geophysical techniques: 3D analyses and seismic responses.

In the last decade, there have been growing applications of long-term continuous ambient seismic noise systems to monitor landslides and potentially unstable rock sites. Two mains monitoring parameters can be alternatively or concurrently extracted from noise recording at potentially unstable sites: the fundamental resonance frequency of the unstable compartments can be derived from noise spectral analysis. The detection of irreversible drops in resonance frequency values and/or of negative velocity changes uncorrelated with external meteorological factors is of primary interest. In this work, there are two seismic stations were installed on either side of the Bossea cave. From the use of these stations, the goal is to understand and study the climate changes along the slides of the Bossea, analyzing the data from a geophysical and geomatic point of view. In synthesis, the geomatic part is based on the use an open-software that allows to create a 3D model, an orthophoto and DSM model of the Bossea area and the imagines are collected using a drone. Instead, the geophysics part is based on the data, that are collected via two seismic stations. The data are referring a period between 2/12/2021 and 10/07/2022. The first step is to analyze the data, using a spectral analyses approach and combinate the graphs with the meteorological situation: temperature, precipitation and wind situation. Moreover, other approach is the microseismicity analyses, in which it’s possible to estimate the frequency values related to the different situation recorded by the data from two seismic stations. In conclusion, from the analyses, it’s possible to see a correlation in different periods. In fact, the low frequency curve present in the periods of December and January does not seem to be connected to rainy or snowy events as in these months there is no abundant rainfall, on the contrary in the month of February they are completely absent and in general it appears that in the months December-January-February rainfall is almost zero compared to March-April-May-June. In summary, at the end of the work after various graphs and studies it can be deduced that the results obtained depend on several factors such as: rockfall or seismic events, that can depend on the climate variations, but also at other aspects. For the future, a first step to improve could be the use of a non-open software, which would bring better advantages to the work, not only in terms of the quality of the work, but also in terms of the number of software used.