Advanced Geological Services

Providing Comprehensive Geophysical Solutions

Advantages:

Seismic methods provide a detailed, cross-sectional image of the subsurface. The data can indicate the presence of important geological features and their physical characteristics (orientation, seismic velocity, density). Three dimensional depth-to-target contour plots can be generated. The data collection is non-destructive and non-intrusive.

Limitations:

Depending on the target, seismic methods may require more field and office time to complete than other geophysical methods.  Cultural noise vibrations can adversely affect the seismic data quality.

Typical Seismograph

Applications and Methods:

AGS uses seismic refraction and reflection methods to map geologic and hydrogeologic features in the subsurface. The data can be acquired on land and in a marine environment. AGS uses seismic techniques to determine:

· Overburden or Landfill Thickness

· Bedrock Configuration in Two or Three Dimensions

· Stratigraphic or Lithologic Mapping

· Dip and Orientation of Geologic Layers

· Fault, Fracture, Weathered, and Shear Zone Presence

· Continuity of Confining Layers

· Depth to Groundwater

· Elastic Properties of Sediments and Bedrock (P– and S-wave velocities)

· Pathways of Groundwater Flow

· Void and Sinkhole Detection

· Bedrock Rippability

· Landslide Evaluation

· Vibration Monitoring

The seismic method is based upon the transmission of seismic waves into the subsurface and the recording, measurement, analysis, and interpretation of the resulting waveforms. Detailed cross-sectional images are generated that provide information on the depth, thickness, and velocity of the target horizons (bedrock, water table, lithologic units), and their lateral variations along the line. Various filtering techniques and post-acquisition processing methods can be implemented to enhance the resolution characteristics and interpretability of the data sets. Seismic information can be obtained within a depth range of five feet to several thousand feet.

Sample Seismic Refraction Profile with Rock Velocities

(Click to Enlarge…)

Seismic