[1] We analyze vertical component body and surface waves for 10 Mw > 5 earthquakes, recorded by ocean bottom seismometers at regional and teleseismic distances. Through waveform modeling, we place new constraints on along-axis variation in temperature and partial melt beneath the eastern Pacific ridges. The resulting best fit models show over 9% variation in average lithosphere shear velocities...

W ith the advent of near-equilibrium growth techniques, it is now possible to synthesize virtually any type of crystalline nanostructure. Researchers can exert a fine control over size, shape and surface chemistry to tailor the properties of their nanomaterial to specific applications relevant to energy conversion, sensing, electronics and photonics. Once in a device, these nanostructures are f...

Using multiple deployments of an 80-element, three-component borehole seismic array stretching from the surface to 2.3 km depth, we examine recordings of chemical explosions to better understand the generation of shear waves by explosive sources. The well is near vertical in the upper 1.5 km and gradually transitions to a dip of 38 degrees at the deepest recording location. The chemical shots a...

Rocks are far from being isotropic and elastic. Such simplifications in modeling the seismic response of real geological structures may lead to misinterpretations, or even worse, to overlooking useful information. It is useless to develop highly accurate modeling algorithms or to naively use amplitude information in inversion processes if the stress-strain relations are based on simplified rheo...

in many seismological applications, the earth is considered as a perfectly elastic, homogeneous, and isotropic body. although this assumption is approximately valid, it is known that seismic waves pass through the real earth that is anelastic, inhomogeneous and anisotropic.  we consider four processes that can reduce wave amplitude, i.e.: geometrical spreading, scattering, multi-pathing, and an...

Surface wave studies have shown that the transition region of the upper mantle, Bullen's Region C, is not spread uniformly over some 600 km but contains two relatively thin zones in which the velocity gradient is extremely high. In addition to these transition regions which start at depths near 350 and 650 km, there is another region of high velocity gradient which terminates the lowvelocity zo...

Measurements of attenuation for the Earth's longest period modes can be significantly biased by the effects of frequency splitting. Using our previously developed methods of time domain synthesis of split normal modes, we measure Q without such a bias. We also conduct numerical experiments to confirm the errors in Q measurements which result from neglecting the effects of splitting. In contrast...

The attenuation of seismic waves is a direct measure of the absorption due to nonelastic proc~ esses in the earth. The well known difficulties in obtaining body wave amplitude decrement data have been avoided by studying the spectral ratios of multiple ScS and sScS phases from two deep focus earthquakes recorded at near normal incidence. The average Q, for shear, in the mantle is about 600 for ...

Anelasticity, as suggested by Zener / I / in 1948, gives rise to internal friction which is independent of the strain amplitude. The internal friction which increases with an increase of strain amplitude was explained by Koehler /2/ and Granato and Liicke /3/ in terms of vibration string and unpinning of dislocations. Early in 1949, ~d /4, 5/ observed in slightly cold-worked dilute aluminium-co...