Calculation of Ground Rotational Motions Using Seismic Array Data

This article gives a description of our first study on ground rotational motion and its preliminary results. The ground rotational motions around vertical axis were obtained using near-field translational records of a temporal seismic array with observational distances of 1.8 to 2.7 km. The sources used are explosions with explosive of 500 kg for each. Ground rotational velocities were calculated using the space derivatives of the horizontal components of translational velocities from the array. The peak ground rotational velocities (PGRV) are approximately 30 to 57 μrad/s. Our results are very close to those from Wassermann et al. (2009), who used both a seismic array and a rotational sensor to record an explosion in Germany and obtained PGRV values of about 50 μrad/s. Their explosives are 150 kg, only one third of ours, but their observational distance is 250 m, much less than ours.