Reflection of a seismic wave from a plane interface between two elastic media does not depend on the frequency. If one of the media is poroelastic and fluid-saturated, then the reflection becomes frequency-dependent. This paper presents a low-frequency asymptotic formula for the reflection of seismic plane p-wave from a fluid-saturated porous medium. The obtained asymptotic scaling of the frequ...

Introduction High-resolution seismic reflection has been successfully used to delineate preferential pathways within groundwater systems that represent corridors for contaminant movement in a wide variety of challenging hydrologic settings, many in settings where other methods and/or monitor wells have not been enlightening. For more than four decades, seismic reflection has found utility addre...

[i] We show that ocean temperature profiles can be accurately recovered using only acoustic methods employed at the sea surface. Using a towed air gun array and a hydrophone streamer, thermohaline boundaries are ensonified at a suite of frequencies and angles, yielding travel time trajectories and reflectivities. These data are inverted via full waveform inversion to estimate sound speed and, s...

Wave propagation in heterogeneous media is not only characterized by reflection, transmission and conversion of seismic energy but also by effects such as scattering and tunneling and can be observed on many scales. We investigate elastic wave propagation in the lower crust of the earth. It is remarkable that distance and time scales in a deep crustal reflection problem can be easily transforme...

1999 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Introduction During April 1999, the U.S. Geological Survey (USGS) conducted a 13-day cruise in the G...

Seismic reflection and refraction images illuminate the San Andreas Fault to a depth of 1 kilometer. The prestack depth-migrated reflection image contains near-vertical reflections aligned with the active fault trace. The fault is vertical in the upper 0.5 kilometer, then dips about 70 degrees to the southwest to at least 1 kilometer subsurface. This dip reconciles the difference between the co...

Shallow high-resolution seismic reflection techniques proved valuable in detecting, delineating, and advancing interpretations of a regional fault and associate local structural features previously speculated from sparse well data in northeastern Wisconsin. This seismic survey was the first of its kind in this part or Wisconsin and provided solid evidence that the method will work well in this ...

Fluid migration pathways in the subsurface are heavily influenced by pre-existing faults. Although studies of active fluid-escape structures can provide insights into the relationships between faults and fluid flow, they cannot fully constrain the geometry of and controls on the contemporaneous subsurface fluid flow pathways. We use 3D seismic reflection data from offshore NW Australia to map 1...

In order to mitigate against possible impacts of seismic surveys on baleen whales it is important to know as much as possible about the presence of whales within the vicinity of seismic operations. This study expands on previous work that analyzes single seismic streamer data to locate nearby calling baleen whales with a grid search method that utilizes the propagation angles and relative arriv...

We present an imaging method that creates a map of reflection coefficients in correct one-way time with no contamination from internal multiples using purely a filtering approach. The filter is computed from the measured reflection response and does not require a background model. We demonstrate that the filter is a focusing wavefield that focuses inside a layered medium and removes all interna...