The seismic computed tomography （CT） method is derived from the basic principles of X-ray section scanning first applied in medical science. The method records P-wave arrivals between shots and receivers in separate...The seismic computed tomography （CT） method is derived from the basic principles of X-ray section scanning first applied in medical science. The method records P-wave arrivals between shots and receivers in separate boreholes. Using the velocity information from 2D seismic P-wave arrival inversion, we can determine the distribution of velocity in rock and soil bodies. This paper introduces a practical case of using the seismic CT method for detecting the structure of the rocks for tunnel engineering and to utilize SIRT algorithms for doing first arrival time iterative inversion. Compared with other exploration methods, it is more efficient and accurate.展开更多
We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids...We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids to solve the wave equations and implement the calculation on a parallel PC cluster to improve the computing efficiency. Features of global SH-wave propagation are firstly discussed for a 100-km shallow and900-km deep moonquakes, respectively. Effects of frequency range and lateral variation of crust thickness are then investigated with various models. Our synthetic waveforms are finally compared with observed Apollo data to show the features of wave propagation that were produced by our model and those not reproduced by our models. Our numerical modeling show that the low-velocity upper crust plays significant role in the development of reverberating wave trains. Increasing frequency enhances the strength and duration of the reverberations.Surface multiples dominate wavefields for shallow event.Core–mantle reflections can be clearly identified for deep event at low frequency. The layered whole Moon model and the low-velocity upper crust produce the reverberating wave trains following each phases consistent with observation. However, more realistic Moon model should be considered in order to explain the strong and slow decay scattering between various phases shown on observation data.展开更多
文摘The seismic computed tomography （CT） method is derived from the basic principles of X-ray section scanning first applied in medical science. The method records P-wave arrivals between shots and receivers in separate boreholes. Using the velocity information from 2D seismic P-wave arrival inversion, we can determine the distribution of velocity in rock and soil bodies. This paper introduces a practical case of using the seismic CT method for detecting the structure of the rocks for tunnel engineering and to utilize SIRT algorithms for doing first arrival time iterative inversion. Compared with other exploration methods, it is more efficient and accurate.
基金supported by the National Natural Science Foundation of China(Grants 41374046 and41174034)
文摘We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids to solve the wave equations and implement the calculation on a parallel PC cluster to improve the computing efficiency. Features of global SH-wave propagation are firstly discussed for a 100-km shallow and900-km deep moonquakes, respectively. Effects of frequency range and lateral variation of crust thickness are then investigated with various models. Our synthetic waveforms are finally compared with observed Apollo data to show the features of wave propagation that were produced by our model and those not reproduced by our models. Our numerical modeling show that the low-velocity upper crust plays significant role in the development of reverberating wave trains. Increasing frequency enhances the strength and duration of the reverberations.Surface multiples dominate wavefields for shallow event.Core–mantle reflections can be clearly identified for deep event at low frequency. The layered whole Moon model and the low-velocity upper crust produce the reverberating wave trains following each phases consistent with observation. However, more realistic Moon model should be considered in order to explain the strong and slow decay scattering between various phases shown on observation data.
