Plans call for five T-phase stations to be installed as part of hydroacoustic segment of the International Monitoring System (IMS), for use in detecting nuclear explosions in the oceans. The ability to detect T-phase signals at the seismic T-phase stations relies on an understanding of the transition from ocean-borne acoustic energy to seismic energy. Observations of the seismic T-phase indicat...

Deciphering the origin of seismic velocity heterogeneities in the mantle is crucial to understanding internal structures and processes at work in the Earth. The spin crossover in iron in ferropericlase (Fp), the second most abundant phase in the lower mantle, introduces unfamiliar effects on seismic velocities. First-principles calculations indicate that anticorrelation between shear velocity (...

The late seismic coda may contain coherent information about the elastic response of Earth. We computed the correlations of the seismic codas of 101 distant earthquakes recorded at stations that were tens of kilometers apart. By stacking cross-correlation functions of codas, we found a low-frequency coherent part in the diffuse field. The extracted pulses have the polarization characteristics a...

[1] The geodetic velocity and strain rate patterns in Anatolia constrain the rheology of the lithosphere, once compared with thin shell finite element tectonic model predictions. Geodetic and modeled deformation favors a hard lithospheric rheology, responsible for the high EastWest horizontal velocities in the center of Anatolia, between 39 –41 N, in proximity of the North Anatolian Fault. The ...

A cooperative program of seismic refraction profiling was completed in the vicinity of the Puerto Rico Trench by Hudson Laboratories, Woods Hole, Lamont, and Texas A. & M. Profiles completed near the western end of the Trench were analyzed at Hudson Laboratories. Five seismic layers are indicated below the water layer. The thickness/velocity relationships are as follows: 5.1 km of 1.5 km/sec. (...

In crosswell seismic experiments, seismic sources are red in one well, and the waveeelds generated are measured in another well. The goal of the crosswell seismology is to nd physical parameters, especially the velocities, of the rocks between the wells from these measurements. This amounts to the mathematical problem of solving a coeecient inverse problem of the multidimensional acoustic wave ...

Oil and gas production from tight, fractured reservoirs (sandstone, carbonates and shale) has increased significantly over the last decade. These hard rock targets are often characterized by vertically aligned fractures (i.e. HTI) embedded in a layered sequence (i.e. VTI). In this geologic setting, seismic velocities and η can vary with azimuth and depth. This is orthorhombic anisotropy and can...

Efficient numerical seismic wavefield modelling is a key component of modern seismic imaging techniques, such as reverse-time migration and full-waveform inversion. Finite difference methods are perhaps the most widely used numerical approach for forward modelling, and here we introduce a novel scheme for implementing finite difference by introducing a time-to-space wavelet mapping. Finite diff...

Rock physics modeling aims to provide a link between rock properties, such as porosity, lithology, and fluid saturation, and elastic attributes, such as velocities or impedances. These models are then used in quantitative seismic interpretation and reservoir characterization. However, most of the geophysical measurements are uncertain; therefore, rock physics equations must be combined with mat...

The purpose of this research was to test the proposition that the mantle beneath New York and Southern New England is divided into several "anisotropic domains" that are the seismic expression of the plate tectonic process of "terrain accretion". Were such the case, we would expect different directions of the shear wave fast direction and different mean shear wave velocities in each of the seve...