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Geophysics - Vibration & Noise - Rock Mechanics

Providing Quality Geophysical Consulting Services since 1984

The Seismic Refraction Method

The seismic refraction method provides information that can be used in:

 Seismic refraction explorations consist of measuring the time required for a seismic impulse to travel from a seismic source to a receiving transducer. An explosive device, an air gun, a weight dropped from a truck or a hammer striking a steel plate is typically used for the seismic source and twelve or more vertical geophones are used for the receiving transducers. The choice of the seismic source depends upon the length of the seismic line, the degree of resolution desired, and the environmental suitability of a particular source.

A signal enhancement seismograph records signals from the geophones. By analyzing the arrival time of the seismic wave as a function of distance from the seismic source, the seismic velocities Seismic Refraction Surveyof the underlying soil/rock units and the depth to geologic contacts can be determined. The geophone spacing and the distance between the seismic source and the first geophone are designed to obtain the needed penetration and resolution. Application of the method is generally limited to areas where seismic velocity increases or is constant with depth.

Earth Dynamics uses  state-of-the-art  forward and inverse modeling and ray tracing techniques to analyze seismic refraction data.  The modeling techniques can detect both lateral and vertical variations in seismic velocity. An example of a seismic refraction model is shown below.

Example Seismic Refraction Profile