Microseisms at Scott Base
The seasonal variation of the pack ice surrounding the Antarctic continent has a great effect on the levels of microseismic activity at Scott Base. Microseismic storms are in general of two types, one with periods 1–3.5 s the other with periods 4–10 s. The short-period activity is due to events with...
| Published in: | Geophysical Journal International |
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| Main Author: | |
| Format: | Text |
| Language: | English |
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Oxford University Press
1960
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| Online Access: | http://gji.oxfordjournals.org/cgi/content/short/3/4/381 https://doi.org/10.1111/j.1365-246X.1960.tb01713.x |
| Summary: | The seasonal variation of the pack ice surrounding the Antarctic continent has a great effect on the levels of microseismic activity at Scott Base. Microseismic storms are in general of two types, one with periods 1–3.5 s the other with periods 4–10 s. The short-period activity is due to events within the Ross Sea and is at a maximum during January and February when the Ross Sea is clear of ice. The long-period activity has a maximum during March and April and this is thought to be due to swell from peripheral cyclones penetrating the Ross Sea and creating microseisms after passing the continental shelf. It is found that the microseisms of any period ( T ) have a limiting amplitude ( A max ) and that for the short-period microseisms A max ∝ T 4.2 while for the long-period microseisms A max ∝ T 6.0. The difference between these two relationships can be satisfactorily explained on the basis of frequency selective decay of the waves causing the long-period microseisms as these waves travel from the cyclone area to the continental shelf. The fourth-power relationship between maximum amplitude and period is similar to that obtained for single storms in America by Romney. It is suggested that this relationship might provide a useful test for a quantitative theory of microseisms, such as the standing wave theory, or alternatively that it can be used to investigate transmission and absorption processes in the crust. The data appear to confirm the requirement of sea roughness for the generation of microseisms, the half-period relationship between microseism and sea wave periods, and the role of the continental shelf and other crustal features as barriers to microseisms of periods less than 7½ s |
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