Sea Ice Thickness Measurements Using Shear Wave Reflections

• Main Authors: Vance,George P., Benefield,Daniel D., Egan,Dennis M.
• Other Authors: COAST GUARD ACADEMY NEW LONDON CONN
• Format: Text
• Language: English
• Published: 1971
• Subjects: Snow; Ice and Permafrost; (*SEA ICE; THICKNESS); (*ALASKA; SEA ICE); MEASUREMENT; SEISMIC WAVES; REFRACTION; ULTRASONIC RADIATION; ACCELEROMETERS; OSCILLOSCOPES; SEISMIC REFRACTION METHOD; Barrow; Ice; permafrost; Point Barrow; Sea ice; Alaska
• Online Access: http://www.dtic.mil/docs/citations/AD0739743; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0739743

Because of the lack of success in measuring sea ice thickness with normal acoustic means, a method utilizing shear waves or 'S' waves was tried during the summer of 1971 off Point Barrow, Alaska. A 551A*Textronic oscilloscope and polaroid camera were used to record the signals received. Two Columbia High Capacity accelerometers were used for triggering the scope and obtaining the return signal. A three pound sledge-hammer impacting on a six inch diameter steel plate was used as the 'S' wave source. Results were obtained in ice thicknesses from 7.0 feet to 21.0 feet thick. An average 'S' wave speed in sea ice of 6.56 feet per millisec was used. In comparing the recorded signals with physically measured thicknesses, the average error was found to be 6.6%. (Author)