نتایج جستجو برای: seismic refraction
تعداد نتایج: 44547 فیلتر نتایج به سال:
The inversion of seismic travel-time data for radially varying media was initially investigated by Herglotz, Wiechert, and Bateman (the HWB method) in the early part of the 20th century [1]. Tomographic inversions for laterally varying media began in seismology starting in the 1970's. This included early work by Aki, Christoffersson, and Husebye who developed an inversion technique for estimati...
Characterization of material changes with depth (profiles) in many landfill sites can be problematic for some conventional geophysical methods. Localized anomalies within the landfill can complicate mapping of underlying layers, and layered-model techniques are inappropriate for imaging laterally discontinuous landfills. Recently-developed geophysical hardware and software tools provide the opp...
Pletser et al. performed a seismic-refraction survey on Devon Island with the goal of assessing the feasibility of astronauts carrying out such operations on Mars to detect subsurface water. We demonstrate that the seismic analysis is fundamentally flawed. The survey performed in this test will likely bear little resemblance to future crewed geophysical surface operations, and better methods ex...
The seismic methods are the most powerful existing technique to image the structure of the Earth’s subsurface. Depending on the system layout, the seismic methods can be divided into near-vertical reflection (NVS) techniques and wide-angle reflection/refraction (WAS) techniques. In contrast to NVS, the development of WAS preprocessing tools has deserved only minor attention to date and most exi...
[1] A single plane fracture with an axially symmetric stress distribution behaves as a seismic lens that focuses seismic energy to a beam ‘‘waist’’ at a focal plane. Both phase and amplitude effects on a seismic wave propagating across the fracture contribute to the lensing behavior. Radial gradients in the fracture specific stiffness cause wave refraction through a radially varying group time ...
In this paper, we are interested in determining the seismic velocity of a shallow under-ground layer from refraction traveltimes measures. We present a study case taken from an experimental seismic survey. The study case is a wide-angle seismic inversion using experimental traveltimes measures and based on ray tracing technique and genetic algorithms. The hypothesis on the velocity distribution...
Compressional(Vp) and shear-wave (Vs) velocities were determined within earthen levees on the Rio Grande River in south Texas, south New Mexico and New Orleans. A loosely fitting relationship was developed to better characterize the internal condition of the levees. Seismic data were incorporated with surface observations, existing core taken from the levee, and airborne EM data acquired. Sever...
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