John Clark at Bay Geophysical, located in Traverse City, Michigan, has developed a P & s-wave land streamer that is based on an initial design by Dr. Tomio Inazaki at the Geological Survey of Japan. This streamer utilizes a fabric strap as the tow device and steel plates as the coupling devices and works well on paved roads and smooth surfaces.

Bay's land streamer on a gravel road, imaging the subsurface using energy from Bay's shear-wave vibrator

Geophones are mounted to a fabric strap

Geophones are housed in an Oyo GeoSpace 2-component case which is capable of accommodating either two orthogonal horizontal geophones or a vertical and a horizontal geophone.  The aluminum plate at the top provides a means of attaching the geophone to the bottom plate while simultaneously insuring that the majority of the transducer mass is kept close to the ground.  Unlike other designs, John's streamer can be configured with geophone spacings of 1-5 feet in increments of 1 foot. The streamer is sectionalized, each section 25 feet in length

Coupled with Bay Geophysical's patented micro- vibrator, this device has thus far proven to be effective for the acquisition of shear wave reflection seismic data.  The portability of the vibrator allows for split spread application.  To date, this streamer has been tested solely in the shear wave mode of application.  The streamer and vibrator are portable enough to be deployed from small vehicles and transported by air.

A comparison of land streamer and geophone collected data is shown below from a site in southern Illinois.  This data comparison was obtained during the first production test of the land streamer.  The bright reflection at 100 milliseconds is a coal seam approximately 50 feet deep.  The land streamer data is the section on the left. While there were some minor differences in reflection signature between the geophones and the land streamer, the sections were sufficiently similar to warrant additional acquisition with the streamer.

Bay Geophysical's shear-wave high-resolution vibrator.

To date, the streamer has been tested against geophones in several locations around the United States including Florida, Illinois, Michigan, California, and Nebraska.  The seismic section opposite is a section from urban Los Angeles, California, taken in an area where there was severe vehicular and pedestrian traffic. The micro-vibrator/land streamer combination effectively overcame the ambient noise to depths of at least 200 feet.