I really enjoyed Greg Baker s company while he was here. I mentioned July 19 that he was a geophysicist from SUNY-Buffalo who would be doing some seismic studies on the glacier and the surrounding area. I was very interested in what he was doing and the physics behind it all. He was always more than willing to talk and answer any questions that I had and for that I am most grateful. What he was doing here was called Active Source P-wave Seismology.
P waves are longitudinal waves that transmit energy through materials.
A longitudinal wave is one in which the vibration or disturbance is back and forth along the line of travel. Sound is a good example of a longitudinal wave and in fact he was using sound waves in the ice. By using a sledge hammer or a gun-like device a disturbance or vibration is sent through the ice that travels out in all directions from the strike just like sound would from a speaker. As the wave passes down through the ice it is reflected by boundaries that exist between different materials, such as that between ice and rock. The reflected wave returns to the surface where it can be picked up with sensors called geophones.