The hydroacoustic segment of the International Monitoring System (IMS) currently being installed for use in verifying compliance with the Comprehensive Nuclear Test Ban Treaty (CTBT), will consist of six hydrophone stations and five supplemental T-phase stations. The ability to detect acoustic signals at T-phase stations relies on an understanding of the acoustic to seismic coupling mechanisms....

Reentrant ventricular tachycardia (VT) is the most common sustained arrhythmia leading to ventricular fibrillation (VF). However, despite more than a century of research, the mechanism(s) of the conversion from reentrant VT to VF have not been elucidated. Based on their different electrocardiographic appearance, reentrant VT and VF have traditionally been thought of as resulting from two widely...

The utility of the multi-channel analysis of surface waves (MASW) seismic method for noninvasive assessment of earthen levees was evaluated for a section of the Citrus Lakefront Levee, New Orleans, Louisiana. This test was conducted after the New Orleans’ area levee system had been stressed by Hurricane Katrina in 2005. The MASW data were acquired in a seismically noisy, urban environment using...

The propagation of a gravitational wave (GW) through a magnetized plasma is considered. In particular, we study the excitation of fast magnetosonic waves (MSW) by a gravitational wave, using the linearized general-relativistic hydromagnetic equations. We derive the dispersion relation for the plasma, treating the gravitational wave as a perturbation in a Minkowski background space-time. We show...

Abstract: Since soil dynamic behaviour is nonlinear in nature therefore a nonlinear viscoelastic model for isotropic materials is proposed in this study. This model is a combination of inelasticity and nonlinear damping. In this model, the shear modulus is taken as a function of the excitation level. The viscosity is assumed to vary nonlinearly. The validity of this model is checked for low amp...

High frequency (8-15 KHz) seismic waves that travel between two boreholes are used to probe the detailed structure of rock in the Los Alamos Scientific Labora:ory Fenton Hill geothermal energy reservoir. Because of the unique ability to control fluid pressure in the reservoir, we can make in situ seismic measurements at different fluid pressures and apply the results of pertinent laboratory mea...

The analysis of seismic wave propagation and amplification in complex geological structures requires efficient numerical methods. In this article, following up on recent studies devoted to the formulation, implementation and evaluation of 3D singleand multi-region elastodynamic fast multipole boundary element methods (FM-BEMs), a simple preconditioning strategy is proposed. Its efficiency is de...

We propose in this paper a modular approach for the problem of traveltime inversion or seismic tomography. This problem consists in the inference of the velocity of wave propagation in the subsurface after an explosion has been produced at the surface, relying on such waves’ traveltimes. These traveltimes are recorded by several receivers on the surface. In the present work, we consider data sy...

In this paper, an overview of the calculation of synthetic seismograms using the Gaussian beam method is presented accompanied by some representative applications and new extensions of the method. Since caustics are a frequent occurrence in seismic wave propagation, modifications to ray theory are often necessary. In the Gaussian beam method, a summation of paraxial Gaussian beams is used to de...