Coda-Based Estimation of Source Parameters of Laboratory Acoustic-Emission Events

• DOI: 10.5194/egusphere-egu23-1330
• Publication Date: 2023-02-22T14:38:43Z
• Authors: Tatiana Kartseva; Nikolai Shapiro
• Keywords: Coda; Logarithmic scale; SIGNAL (programming language)

We propose an approach that is aimed to enrich the catalogs of acoustic emission events recorded in laboratory experiments with such parameters as seismic moment and corner frequency. Because difficulty separation direct waves in performed on small samples, we use coda are composed reverberation of field tested sample. After multiple reverberations, resulting wavefield can be approximated nearly homogeneously distributed over sample and with signal amplitudes decaying exponentially time (linearly a logarithmic scale).Within the framework this model, frequency-dependent amplitude at any time is described combination source spectra, decay rate combining internal attenuation reverberation losses, sensor response. One main difficulties with laboratory sensors very difficult calibrate their absolute response function most cases remains unknown. With simple reverberation model, logarithms different times for multiple events by system linear equations solve least-square sense to find coda-decay rates, relative spectra responses. In a next step, compute spectral ratios between eliminate sensor responses estimate frequencies relative seismic moments.We provide details our data analyses technique present time-dependent frequency vs diagrams two granite Voronezh massif Berea sandstone under pseudo-triaxial loading. The dependence close cubic frequently estimated tectonic earthquakes observed first stages both when confining pressure steps applied intact rock therefore pre-existing inhomogeneties. applying axial load changes stress-drop being observed: higher stress-drops prevailing lower sandstone. Also there significant difference Gutenberg-Richter relation these experimental conditions observed.