Abstract
Characteristics of ground motions caused by small dynamite charges were studied. Seismometers were set up at various depths within bore-holes, and varying the depth of shot-hole, the explosive waves were recorded.
In this experiment, surface waves which could be considered as RAYLEIGH and SEZAWA waves were observed.
The characteristics of these waves are as follows.
RAYLEIGH wave:
The wave velocity is 60m/sec.
The period of motion is about 0.22sec.
The amplitude decreases exponentially with depth.
SEZAWA wave:
The wave velocity is 500m/sec.
The period of motion is about 0.1-0.08sec.
As to the vibration mode, there is one node in the upper layer.
These results are in good agreement with those predicted by the theories of RAYLEIGH and SEZAWA waves.
