GTA's Geologists and Geophysicists use physical properties (i.e., gravity, electricity, density, magnetic, electromagnetic, etc.) to remotely sense into the subsurface of the earth. Geophysical techniques are known as "non-invasive, non-destructive" techniques because they rarely require that the ground be excavated or even disturbed. Geophysical methods are especially ideal at sites where no disturbance is allowed. GTA professionals evaluate the appropriate geophysical methods to utilize, which is essential to the success outcome and may result in significant saving and improved data over more traditional site investigation methods.

Geophysical services include:

• Electrical Resistivity & Conductivity
• Ground Penetrating Radar(GPR)
• Gravity
• Magnetometry
• Seismic Refraction & Shear Wave
• Very Low Frequency Radio (VLF)
• Spontaneous Potential (SP)