How Volterra is used for Magnetotellurics

Volterra Acquisition units are capable of acquiring Electric field (Ex, Ey) and Magnetic field (Bx, By, Bz) data simultaneously. The data can be collected in a variety of configurations from a simple 4-component single site MT sounding to complex 3D Full Tensor MT arrays consisting of numerous electric dipoles and multiple B-field sites. The latter configuration can be efficiently integrated with a 3DIP survey utilizing the same electric dipoles. The MT results complement the resistivity results to provide greater depth of investigation. Unique to SJ Geophysics is the acquisition of multiple short-interval MT readings during IP acquisition quiet periods, although we can also acquire longer periods over the evening hours.

The Volterra system utilizes very sensitive Induction Magnetometer (B-field coil) that provide a frequency range between 0.1 Hz to 20 kHz. In addition, fluxgate magnetometers are available to acquire responses of lower frequencies. For survey regions where quality data is not acceptable due to a weak natural signal or contamination by local cultural noise, the addition of a controlled source can be incorporated. Collection of controlled data in a specific frequency band is referred to as CSAMT.