Seismology Photos

Albert P. Crary, Deputy Chief Scientist of the NAS's US-IGY Antarctic program, reads a seismograph record taken on one of the traverses he led during his two-and-a-half years in Antarctica.

Scientists making seismic soundings on Cape Roydes, McMurdo Sound, Antarctica. The instrument is a 45-channel seismic recorder, used to determine ice thickness by measuring the time taken by sound waves traveling from a surface explosion to the underlying strata.

Seismic explosion on the Byrd IGY Station oversnow traverse. The explosion was made to determine the thickness of the ice. Shock waves from the explosion traveled downward to the bedrock below the ice and echoed to the surface, whre they were picked up by receiving equipment. The time involved for the waves to reach the bedrock and return indicates the thickness of the ice. The sno-cat vechicle at the left contained the amplifiers and recorder used to record the seismic shock.

Pictured here is a long period horizontal seismograph. This instrument, which was used extensively in the USNC-IGY seismology program, measures ground motion in the east-west direction in the period range 2 to 450 seconds.