Underground Imaging Using Shear Waves

Abstract

A method using shear waves has been proposed to detect buried relics and ruins at shallow depths. Pulse-compression processing is examined for improving the underground imaging resolution. Both down-chirp signals (600–300 Hz) and 1kHz burst signals can be generated using a super-magnetostriction vibrator as a sound source. First, pulse compression is simulated in the lab to confirm the resolution of underground images. Exploration experiments were then conducted at Heijyo-kyo in ancient Nara. The underground images are obtained from these experiments. We confirmed the effectiveness of the pulse-compression method for improving resolution.