The MH-64 and MH-52 are borehole hammers for geotechnical crosshole seismic surveys.

The seismic signals are conveyed to the earth through the water filling the borehole by means of a pulse converter.

The investigation range is from 50 to 150 meters, depending on the seismic transparency of the rock or soil.

The minimum diameter is 56 mm (BQ) for the MH-52 and 75 mm (NQ) for the MH-64. The recommended depth is maximum 200 m.

The hammers are designed to be used in "fast stack" mode, the blow interval being adjustable between 1 and 5 seconds. Both models are equipped with electric motors and piezoelectric trigger sensors with a timing accuracy of few tens of microseconds.

Data recorded with the MH-64 at distances of 10-20m in saturated sand. The diagram above displays a profile band-pass filtered to enhance the P-wave frequencies. The diagram below presents the same profile filtered in the S-wave band (the time scale is compressed six fold with respect to the upper profile).