MBAS

The Multistation Borehole Acquisition System (MBAS) is a digital three-component geophone string used to receive P- and S-waves in dry or water filled boreholes. Up to ten individual stations with tri-axial sensors can be connected. The stations are aligned to ensure that all horizontal sensors are oriented in same direction. The system can be oriented from the surface by a torsionally stiff hose. Each station is clamped to the borehole wall by two pneumatic cylinders. An external trigger can be plugged into the USB interface on surface which is connected to a laptop. The operation is entirely controlled by the acquisition software. A separate seismograph is not required.

Technical Details

Natural sensor frequency: 10 Hz
Sensor arrangement: Tri-axial
Operational depth: Up to 100 m
Max. number of stations: 10
Station interval: 1 or 2 m
Station length: 735 mm
Station diameter: 65 mm
Station weight: 2.5 kg
Cable weight per metre: 460 g
Borehole diameter: 75 mm
Clamping system: Pneumatic cylinders
Orientation: Torsionally stiff hose
Depth indicator: Cable marking every 2 m
Storage: On drum and in

Digitization

Design: MoHo s.r.l.
Power supply: PC USB interface
A/D conversion: 24 bit
Sampling frequencies: 256 to 32768 Hz
Trace length: Max. 4 s
Trigger: TTL, geophone
Software: Soilspy (MoHo s.r.l.)