The seismic waveform propagating perpendicular to the andesite fracture. The elastic waves were excited by applying a burst of sinusoidal wave (trigger time =5.66 µs) with 10 Vp-p and 250 kHz to a PZT (lithium-niobate piezoelectric transducer). The transmitted wave received at the other side is digitized with a dynamic range of 16 bits. The sampling length and rate were 8,192 data points and 50 MHz, respectively. The obtained waveforms are stacked over 200 times to enhance the signal-to-noise ratio.
