The aim of this paper is to construc an image from Moho discontinuity in South America. This result can be obtained through global modeling of Rayleigh waves phase and group velocity (ROSA (1986) and SANTA ROSA (1996)). The initial 2-D inversion model was defined according to the geographic position of each block, sized 10 x 10 degrees by ROSA (1986), in the continent and in the ocean. As a res...

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. (...

Plate tectonics is largely responsible for material and heat circulation in Earth, but for unknown reasons it does not exist on Venus. The strength of planetary materials is a key control on plate tectonics because physical properties, such as temperature, pressure, stress, and chemical composition, result in strong rheological layering and convection in planetary interiors. Our deformation exp...

We present three case studies of traveltime tomography applied to regional imaging of the earth's crust and upper mantle. The first case study investigates the imaging of Poisson's ratio using measurements of compressional and shear wave traveltimes. Inversions schemes that jointly fit both types of traveltime data and that selectively damp the compressional to shear wave velocity ratio are sho...

[1] Stacking of approximately 1500 radial receiver functions recorded at about 80 broadband seismic stations deployed in southern Africa reveals systematic spatial variations in the ratio of crustal P and S wave velocities (F), crustal thickness (H), and the amplitude of the converted Moho phases (R). The eastern Zimbabwe and the southern Kaapvaal cratons are characterized by small H ( 38 km), ...

P waves from regional-distance earthquakes are complex and reverberatory, as would be expected from a combination of head waves, post-critical crustal reflections and shallow-incident P waves from the upper mantle. Although designed for steeply-incident teleseismic P waves, receiver functions (RFs) can also retrieve information about crustal structure from regional P. Using a new computation me...

[1] Large igneous provinces are characterized by magmatic activity on two distinct timescales. While these provinces have total active lifetimes of order 10–30 Ma, most of the erupted volume is emplaced within 1 Ma in many cases. The longer timescale is consistent with plume or tectonic models for mantle melting responsible for flood volcanism, but the shorter “main stage” timescale is enigmati...

One of the main objectives of geophysics is to determine the density at different depths and at different geographical locations. There exist several methods for estimating the density: e.g., we can use seismic data, or we can use gravity measurement. Each of the techniques for estimating the density has its own advantages and limitations: e.g., seismic measurements often lead to a more accurat...