Acoustic velocity varies in deep-water environments.To obtain accurate inversion interpretations,it is necessary to develop a horizontally layered seawater–seabed(HLSS)model with continuously varying velocities.In th...Acoustic velocity varies in deep-water environments.To obtain accurate inversion interpretations,it is necessary to develop a horizontally layered seawater–seabed(HLSS)model with continuously varying velocities.In this work,we used an HLSS model based on wave theory to deduce the Scholte wave dispersion equations and established an HLSS model based on the acoustic velocity profile and the submarine medium parameters of the South China Sea.We studied the dispersion characteristics of Scholte waves and theoretically calculated the amplitude–depth distribution.We also examined the influence of deep-water environments on the dispersion characteristics of Scholte waves.Using the real geological parameters of the Dongsha Islands in the South China Sea,we exploited the spectral element method to simulate seismic wave propagation in the fluid–solid interface and extracted the Scholte wave dispersion curves using multichannel analysis of surface waves(MASW).The consistent theoretical and extracted dispersion curve results verified the accuracy of our method.Numerical experiments showed that the dispersion characteristics of Scholte waves in deep water are weaker than those in shallow water.In addition to the seawater depth and the physical parameters of seabed sediments,the seawater’s variable velocity also influences Scholte wave dispersion characteristics.展开更多
In this paper,the Gaoyou-Baoying M_S4.9 earthquake was analyzed by the geomagnetic harmonic wave amplitude ratios method. The earthquake was an isolated seismic event,before and after which there were no other earthqu...In this paper,the Gaoyou-Baoying M_S4.9 earthquake was analyzed by the geomagnetic harmonic wave amplitude ratios method. The earthquake was an isolated seismic event,before and after which there were no other earthquakes occurred in this region. The dense distribution of geomagnetic observataries provided an advantage condition for the analysis of characteristics of the geomagnetic harmonic amplitude ratios. The analysis results verify the former knowledge of anomaly characteristics of the geomagnetic harmonic amplitude ratio,that is,the anomalous characteristics of the earthquake mostly appeared during the decline-turning-recovery rising process. The results also show that the change of the anomalies was asynchronous at the observatories close to the epicenter, namely, the anomalous characteristics were different between the H and the D components,as well as between the long and short periods.展开更多
Oblique wave interaction with a two-layer breakwater consisting of perforated front and back wall in the presence of bottom undulations is analyzed.Wave characteristics are studied in the framework of small-amplitude ...Oblique wave interaction with a two-layer breakwater consisting of perforated front and back wall in the presence of bottom undulations is analyzed.Wave characteristics are studied in the framework of small-amplitude wave theory,and Darcy’s law is used for flow past porous structures.The varying bottom topography spanned over a finite interval connected by two semi-infinite intervals of uniform water depths.Eigenfunction expansion method is used to handle the solution in the regions of uniform bottom and a modified mild-slope equation along with jump conditions is employed for varying bottom topography.Reflection,transmission,and wave energy dissipation coefficients are obtained numerically by applying the matrix method to understand the effects of several physical quantities such as wavenumber,porosity,and angle of incidence.The transmission coefficient reduces significantly and the wave energy dissipation is high for the present model.Also,Bragg scattering is analyzed in the presence of step-type rippled bottom and presented in this paper.展开更多
基金funded by the National Natural Science Foundation of China (grant no.42074149)the Natural Science Foundation of Jiangsu Province (BK20201318).
文摘Acoustic velocity varies in deep-water environments.To obtain accurate inversion interpretations,it is necessary to develop a horizontally layered seawater–seabed(HLSS)model with continuously varying velocities.In this work,we used an HLSS model based on wave theory to deduce the Scholte wave dispersion equations and established an HLSS model based on the acoustic velocity profile and the submarine medium parameters of the South China Sea.We studied the dispersion characteristics of Scholte waves and theoretically calculated the amplitude–depth distribution.We also examined the influence of deep-water environments on the dispersion characteristics of Scholte waves.Using the real geological parameters of the Dongsha Islands in the South China Sea,we exploited the spectral element method to simulate seismic wave propagation in the fluid–solid interface and extracted the Scholte wave dispersion curves using multichannel analysis of surface waves(MASW).The consistent theoretical and extracted dispersion curve results verified the accuracy of our method.Numerical experiments showed that the dispersion characteristics of Scholte waves in deep water are weaker than those in shallow water.In addition to the seawater depth and the physical parameters of seabed sediments,the seawater’s variable velocity also influences Scholte wave dispersion characteristics.
基金funded by the routine task entitled“The Routine Recognition and Tracking of HVDC's Interference in Geomagnetic Observation”of the Technical Management Group of Electromagnetic Discipline,CEA
文摘In this paper,the Gaoyou-Baoying M_S4.9 earthquake was analyzed by the geomagnetic harmonic wave amplitude ratios method. The earthquake was an isolated seismic event,before and after which there were no other earthquakes occurred in this region. The dense distribution of geomagnetic observataries provided an advantage condition for the analysis of characteristics of the geomagnetic harmonic amplitude ratios. The analysis results verify the former knowledge of anomaly characteristics of the geomagnetic harmonic amplitude ratio,that is,the anomalous characteristics of the earthquake mostly appeared during the decline-turning-recovery rising process. The results also show that the change of the anomalies was asynchronous at the observatories close to the epicenter, namely, the anomalous characteristics were different between the H and the D components,as well as between the long and short periods.
基金Saista Tabssum acknowledges the Institute post-doctoral fellowship grant from Indian Institute of Technology,Bombay.
文摘Oblique wave interaction with a two-layer breakwater consisting of perforated front and back wall in the presence of bottom undulations is analyzed.Wave characteristics are studied in the framework of small-amplitude wave theory,and Darcy’s law is used for flow past porous structures.The varying bottom topography spanned over a finite interval connected by two semi-infinite intervals of uniform water depths.Eigenfunction expansion method is used to handle the solution in the regions of uniform bottom and a modified mild-slope equation along with jump conditions is employed for varying bottom topography.Reflection,transmission,and wave energy dissipation coefficients are obtained numerically by applying the matrix method to understand the effects of several physical quantities such as wavenumber,porosity,and angle of incidence.The transmission coefficient reduces significantly and the wave energy dissipation is high for the present model.Also,Bragg scattering is analyzed in the presence of step-type rippled bottom and presented in this paper.
