GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 GNGTS 2023 The omission analysis determines what are the most important parameters to use when training a neural network to predict dynamic failure in samples of Alzo Granite. Results are strongly dependent on the methods used to define the training parameters but several trends are emerging. Event rate and event amplitude are intuitive, but they differently influence predictions of stress and strain, respectively. Event rate appears relevant only in the early phases, while amplitude seems much more significant during the coalescence/propagation phase. Seismic scattering and source mechanisms also show an early relevance, interpreted as due 1) to the breakup of low frequency surface waves as microcracks begin to coalesce and 2) bursts of tensile events in the enucleation phase and an increase at ~80% UCS, likely related to the crack propagation. Similarly, there is a clear pivot in the importance of seismic velocity during the early stage, but it emerges a progressive increase ~40% UCS whose origin is unclear. We are currently determining if these variations are directly related to the mechanics of the fault zone or are simply an artifact of the processing. References Benson P.M., Thompson B.D., Meredith P.G., Vinciguerra S. and Young R.P.; 2007: Imaging slow failure in triaxially deformed Etna basalt using 3D acoustic-emission location and X-ray computed tomography , Geophysical Research Letters , 34 , doi: 10.1029/2006GL028721. King T., De Siena L., Benson P., Vinciguerra S.; 2022: Mapping Faults with Seismic Scattering 1: A Laboratory Analogue , Geophysical Journal International, 232 (3), March 2023,1590–1599, https://doi.org/10.1093/gji/ggac409. King T., Vinciguerra S., De Siena L., Benson P.; 2021: Source analysis of fault nucleation and formation during laboratory earthquakes , Journal of Geophysical Research-Solid Earth , 126 , e2020JB021059, doi: 10.1029/2020JB021059; King T., Benson P., De Siena L., Vinciguerra S.; 2020: Acoustic Emission Waveform Picking with Time Delay Neural Networks During Rock Deformation Laboratory Experiments , Seismological Research Letters, 92 (2A): 923–932, doi: 10.1785/0220200188 Kwiatek, G., and Y. Ben-Zion; 2010: Assessment of P and S wave energy radiated from very small shear-tensile seismic events in a deep South African mine , J. Geophys. Res. Solid Earth, 118 , 3630–3641, doi:10.1002/jgrb.50274. Corresponding author: sergiocarmelo.vinciguerra@unito.it