Vibroseis

Vibroseis is a seismic source method used in land seismic surveys to generate controlled acoustic energy for reflection seismology. A truck-mounted vibrator applies a time-varying, low-frequency sweep to the ground via a pad or plate, producing repeatable energy that is recorded by geophones.

The source waveform is a deliberate sweep (adaptive in duration and frequency), typically lasting several seconds and spanning a few hertz up to a few tens of hertz. The recorded traces are processed by correlating or deconvolving with the known sweep to retrieve the ground response, followed by stacking to improve signal-to-noise and achieve deeper penetration.

Advantages include environmental safety compared with explosive sources, repeatability, and the ability to tailor the bandwidth and energy. Vibroseis provides good low-frequency energy for deep imaging and works over varying ground conditions with proper coupling and pad design.

Equipment and operation involve hydraulic vibrators mounted on a vehicle, ground pads, and a control system to generate the sweep; field practice requires careful site preparation and calibration to ensure accurate source wavelets and ground coupling.

Limitations include dependence on solid pad-ground coupling, complex source wavelets that require calibration, and more demanding processing and logistics. It is widely used in onshore oil and gas exploration, geothermal and engineering seismology, and calibrated crustal studies.