Osamu Nishizawa

TL;DR: In this paper, a detailed time-space distribution of acoustic emission (AE) events during the catastrophic fracture of rock samples containing a preexisting joint or potential fracture plane is obtained under triaxial compression using a high-speed 32-channel waveform recording system, and the results are discussed with respect to the prediction and characterization of catastrophic fault failure.

TL;DR: In this paper, the detailed faulting process of a naturally healed fault containing geometric and mechanical asperities in a granitic porphyry sample, based on data collected with a high-speed acoustic emission (AE) waveform recording system, was examined using the detailed spatio-temporal distribution of AE hypocenters.

TL;DR: In this paper, a case study of time-lapse seismic monitoring of carbon dioxide (CO2) injection by travel-time delay tomography is presented, which applies the 3D finite-frequency wavefield theory which in seismology is known as the banana-doughnut theory.

TL;DR: In this article, the effects of short-wavelength random heterogeneity on seismic waves were evaluated using a compression-mode piezoelectric transducer attached to one side of the block, and the waveforms were measured at a 10-mm radius circular array with a 2-degree spacing, located on the other side.

TL;DR: In this paper, a laboratory physical model experiment in ultrasonic frequency range was performed to understand the scattering characteristics of seismic shear waves in the Earth, and the strength of scattered wave excitation and the distortion of shear-wave polarization as a function of the correlation distance.