Powerful seismovibrators as a possible source of acoustic and electromagnetic disturbances

The observations of the disturbances of the acoustic, electric and magnetic fields at various distances from a vibroseismic source (5-12 Hz frequency range) are presented. Two centrifugal vibrosources (VS) with sinusoidal vib rational force onto the ground of 100 and 40 tons are used. Infrasonic sign als are reliably recorded at distances up to 50 km. When the acoustic signa l is large, a seismic signal with the same arrival time is also detected. M agnetic and atmospheric electric fields are detected at distances of severa l kilometers. These signals have practically zero lag time and precede the acoustic and seismic signals. The disturbances caused by the VS were also r egistered by telluric field measurements at distances up to 2 km from the s ource. (C) 2000 Elsevier Science Ltd. All rights reserved.