I present a finite-difference method for modeling P-SV wave propagation in heterogeneous media. This is an extension of the method I previously proposed for modeling SH-wave propagation by using velocity and stress in a discrete grid. The two components of the velocity cannot be defined at the same node for a complete staggered grid: the stability condition and the P-wave phase velocity dispers...

As part of a joint Sino-U.S. research project to study the deep structure of the Tibetan plateau, 11 broadband digital seismic recorders were deployed on the plateau for one year of passive seismic recording. In this report we use teleseimic P waveforms to study the seismic velocity structure of crust and upper mantle under three stations by receiver function inversion. The receiver function is...

In \citet{Stangalini20} and \citet{Deb20}, magnetic oscillations were detected in the chromosphere of a large sunspot found to be linked coronal locations where First Ionization Potential (FIP) effect was observed. an attempt shed light onto possible excitation mechanisms these localized waves, we further investigate same data by focussing on relation between spatial distribution wave power ove...

Radiation emitted by an electric dipole consists of traveling and evanescent plane waves. Usually, only the traveling waves are observable by a measurement in the far field, since the evanescent waves die out over a length of approximately a wavelength from the source. We show that when the radiation is passed through an interface with a medium with an index of refraction larger than the index ...

Converted-wave data have been recognized to have potential in complementing conventional compressional data. However, imaging for converted-waves is more difficult mainly due to the need for estimating shear-wave velocities, in addition to compressional-wave velocities. The common practice is to obtain the shear-wave velocity by registering PS and PP images. Despite its low cost, this procedure...

A novel, all-optical method to excite and detect spin waves in magnetic materials is presented. By exploiting the temperature dependence of the magnetic anisotropy, an ultrashort laser pulse is efficiently converted in a picosecond "anisotropy field" pulse that triggers a coherent precession of the magnetization. Recording the temporal evolution of the precessing spins by a time-delayed probe-p...

Soft gamma repeaters are identified as highly magnetized (B≈ 10 14 Gauss) neutron stars. Magnetic stresses induce tec-tonic activity, and field annihilation in faults is the ultimate energy source for the observed γ-ray emission. As a consequence of the crustal cracking, the stored elastic energy is converted into high frequency (kHz) shear waves, that excite nonradial oscillation modes damped ...