Amplitudes of seismic waves on ice sheet in East Antarctica

• Main Authors: Kiyoshi Ito, Akira Ikami
• Format: Report
• Language: English
• Published: Rogional Observation Center for Earthquake Prediction,Faculty of Science,Kyoto University 1984
• Subjects: East Antarctica; Mizuho; Mizuho Plateau; Prince Olav Coast; Antarc*; Antarctica; Ice Sheet; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=637; http://id.nii.ac.jp/1291/00000637/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=637&item_no=1&attribute_id=18&file_no=1

In 1979-81, ten shots were fired in drill holes at the Prince Olav Coast and the Mizuho Plateau, Antarctica, for explosion seismic experiments by JARE-20, -21 and -22. The yield ranged from 10 to 1400kg. An empirical relationship between yield and maximum amplitude of seismic wave was derived for shots in drill holes in ice sheet. This will help to design an adequate charge size for explosion seismic experiments in Antarctica. The maximum amplitudes obtained are compared with those generated from explosion in sea water in Antarctica and in solid rock in Japan. For yields smaller than 500 kg, the logarithm plots of the amplitudes are in a linear relation with the logarithm of yields, and the amplitudes are about 1/5 to 1/8 of those generated in solid rock. For the yields larger than 500 kg, the wave amplitudes in the ice sheet become larger than those estimated from the above relationship. The amplitude of the biggest shot of 1.4t detonated in the ice sheet is nearly the same as that in solid rock in Japan. This is because small shots were fired in shallow drill holes where the ice is very porous, its density is only about 500 kg/m^3. The biggest shot was fired at a depth of 140 m in the ice with a density of 800 kg/m^3 or greater. The maximum amplitudes of seismic waves generated from a 1-t explosion in sea water are about 8 to 10 times larger than those from equivalent explosions in the ice sheet. The relation is similar to the results obtained for shots in sea water and solid rock in and around Japan.