The propagation of seismic waves through Earth can now be modeled accurately with the recently developed spectral-element method. This method takes into account heterogeneity in Earth models, such as three-dimensional variations of seismic wave velocity, density, and crustal thickness. The method is implemented on relatively inexpensive clusters of personal computers, so-called Beowulf machines...

Seismic and acoustic noise from moving tracked vehicles was used to determine the seismic to acoustic signal coupling ratio (SAR) in the ground. The seismic signal received on a geophone contains some energy that has propagated as seismic waves and some energy that couples from acoustic waves to seismic waves in the vicinity of the geophone. We use the frequency domain coherence between the mic...

Received 30 January 2004; revised 14 May 2004; accepted 14 June 2004; published 13 August 2004. [1] Shear velocity properties of D00 beneath the central Atlantic Ocean are explored using predominantly European seismic recordings of intermediate and deep focus (>100 km) South American earthquakes. Broadband data are analyzed and, when possible, corrected for upper mantle models of receiver-side ...

Mapping sparse well data into 3D volumes is a challenging problem. Specifically, as seismic velocity model buildings (VMB) requires 3D velocity and anisotropy volumes, and as most anisotropy estimates are calibrated to borehole data, generating 3D anisotropic models relies heavily on extrapolating sparse well data. This spatial extrapolation problem is ill posed and many subjective decisions ar...

[1] We constrain seismic velocity structure in the Earth’s outer core by analyzing differential travel times, waveforms, and amplitude ratios of several pairs of core phases. We use differential travel times and waveforms of PKPbc-PKIKP at 144 –148 , PKiKP-PKIKP at 120 –141 , PKiKP-PKPBdiff at the PKP caustics distance range (141 –145 ), and differential travel times and amplitude ratios of PKP...

The ice content of the subsurface is a major factor controlling the natural hazard potential of permafrost degradation in alpine terrain. Monitoring of changes in ice content is therefore similarly important as temperature monitoring in mountain permafrost. Although electrical resistivity tomography monitoring (ERTM) proved to be a valuable tool for the observation of ice degradation, results a...

Detection of debris flow occurrence can be efficiently obtained through different types of sensors. A pair of ultrasonic sensors placed at a known distance from each other along a torrent have been used as a method to obtain mean front velocity of debris-flows, in addition to their use as detectors of debris flow occurrence. Also seismic and acoustic sensors have been employed to measure debris...

These shortcomings can be overcome if we have some way to estimate residual statics before velocity analysis. F-X filtered common offset gathers are used by Chan (1996) as the model for residual statics analysis before velocity is available, because the common offset domain is the only dimension in seismic surface geometry which is theoretically independent to the velocity information. Chan (19...

the application of nmo (normal moveout) has been recognized as an effective method of generating quasi-zero-offset traces in traditional common-midpoint processing. artifacts of the nmo method relate to the nmo-stretch effects. conventional application of normal-moveout correction to a common-midpoint (cmp) reflection generates a stretch that increases with offset and decreases with zero-offset...