Geophysical Methods

Olson offers a wide range of geophysical methods for investigating geologic and manmade subsurface conditions

Geophysics is generally used in collaboration with other geologic, geotechnical, or environmental site data to provide details between, below, and beyond available drill hole data. Subsurface imaging can provide information on soil and rock properties, liquefaction potential, rippability and excavatability, subsurface conditions, groundwater conditions, IBC Site Classification (Vs30), ground quality assurance, construction quality control, buried obstacles, etc.

Seismic

Several different seismic methods are used in geophysical surveys. Seismic refraction uses P- and S-wave energy to map vertical and lateral subsurface changes.

Refraction (SRT)

Multi-Channel Analysis of Surface Waves (MASW)

Reflection

Crosshole & Downhole Seismic (CS/DS)

Electrical Resistivity

The Electrical Resistivity (ER) methods are used for locating and mapping groundwater sources, natural groundwater flow paths, groundwater contamination, and archeological remnants.

Electrical Resistivity Tomography

Vertical Electrical Sounding

Induced Polarization

Self Potential (SP)

Electromagnetics

The Electromagnetic method is based on the induction of electrical currents in subsurface conductors by electromagnetic waves which are generated on the surface.

Frequency-Domain Electromagnetics

Time-Domain EM (TDEM)

Ground Penetrating Radar

The GPR method is a wave propagation technique that transmits and receives electromagnetic waves (EM or radio waves).

Surface GPR

Borehole GPR

Gravity
Surveys

Gravity surveys are passive, non-invasive measurements of variations in the Earth’s gravitational field.

Interferometric Surveys

Olson Engineering has the equipment and expertise to offer remote monitoring by interferometric radar to measure movement at landslides, surface mining operations, earthen dams, areas of subsidence, glaciers/avalanches, and volcanoes.

Magnetics

The magnetic geophysical method measures distortions in the Earth’s magnetic field caused by ferrous materials, such as steel, iron, or iron rich rocks and soil.

Geophysical Methods