Seismische Geschwindigkeitsmessung im Karbongestein unter Tage

Abstract

The travel-times of longitudinal waves in sandstone were measured with high accuracy in a mine over distances of 5 to 100 meters; 0.1 mm on the recording film represented 1/50,000 second. The traveltime curves, which reflect the geological particularities in the profile, gave velocities of 4,240 and 4,100 m/sec. The frequencies of the vibrations were between 100 and 500 cycles/sec. The “frequency of the first onset” decreased with increasing distance, from 300 cycles/sec at 5 meters to 180 cycles/sec at 95 meters. Travel-time measurements made in the laboratory with large blocks of rock gave the following average velocities: A rock-salt block, 4,400 m/sec; two coal-blocks, 670 and 450 m/sec; a bore-core of coarse-grained sandstone, 2,800 m/sec.