David Gubbins (1947) British university teacher
Explosions generate elastic waves by an impulsive change in volume in the material. Small explosive charges are used in controlled-source seismic experiments in which the waves penetrate only a few kilometres into the earth.
[Seismology and plate tectonics, 1990, http://books.google.com/books?id=tZRxPzwoChIC&pg=PA12] (p. 12)
Seismology and Plate Tectonics (1990)