oa Laboratory Studies of Surface Waves Using a Laser Doppler Vibrometer

We have performed physical modeling of surface waves using a laser Doppler vibrometer (LDV). Surface wave methods have been applied to both engineering and earth science problems to image S-wave velocity of the Earth. In order to develop the surface wave methods, numerical and physical modelings of surface waves are important. The LDV converts a particle velocity of media to the Doppler shift frequency，and enables us to measure very precise ultrasonic waves. A piezoelectric transducer (PZT) was used as a source of elastic waves. 50KHz to 500KHz elastic waves were observed by using the LDV and PZT. We have measured surface waves propagating a homogeneous half space models and horizontal two-layer models using the LDV and PZT. Theoretical characters of surface waves，such as Rayleigh wave dispersion, have been clearly observed by the physical modeling.