Seismic Linear-Synchronous Motor Vibrator

General Information

Instruments:
Seismic Linear-Synchronous Motor vibrator.

Description:
The Seismic Linear-Synchronous-Motor vibrator is a (transportable) monitoring vibrator for investigations down to depths of one kilometre on land. It allows to generate low-frequency signals such that methods like Full-Waveform-Inversion can be used on the results.

Location:
Laboratory of Geoscience and Engineering, Faculty of Civil Engineering and  Geosciences, Stevinweg 1, Delft (Building #23).

Key Words:
Seismic vibrator, seismic monitoring, LSM vibrator.

Main Application:
Seismic investigations on land, down to one kilometer.

Instrument Specification:
The seismic vibrator, based on Linear Synchronous Motors, allows to generate signals between 2 and 200 Hz with full force. Especially the low-frequency specification, that includes low harmonic distortion at those low frequencies, makes this vibrator unique since its weight is โ€œonlyโ€ some 1250 kg.  Since the signal is generated with motors based on electro-magnets, pseudo-random sweeps  can easily be generated. 6 linear synchronous motors are inside the vibrator, being able to create a force up to 6.7 kN.  The maximum stroke of the vibrator is ยฑ42 mm, the most limiting factor on the low-frequency side.  The vibrator can be used nearly continuously, making it very suitable for seismic monitoring of the shallow subsurface, next to being very suitable for combined use with Full-Waveform Inversion for which the low frequencies are necessary.

Dr. Ir. G.G. (Guy) Drijkoningen

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