Spectral Properties and Source Areas of Storm Microseisms at NORSAR
Spectral estimates from eight microseismic storms recorded by long period vertical component seismometers at NORSAR exhibit distinct spectral peaks in the bands 50-85 mHz and 110-195 mHz. A high frequency third peak (180-250 mHz) is also resolvable in some cases. High resolution frequency wave-numbe...
Main Authors: | , |
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Format: | Text |
Language: | English |
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1976
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Online Access: | http://www.dtic.mil/docs/citations/ADA021450 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA021450 |
Summary: | Spectral estimates from eight microseismic storms recorded by long period vertical component seismometers at NORSAR exhibit distinct spectral peaks in the bands 50-85 mHz and 110-195 mHz. A high frequency third peak (180-250 mHz) is also resolvable in some cases. High resolution frequency wave-number analysis of the storm microseisms yield azimuthal estimates which are accordant with meteorological disturbances over both the North Atlantic Ocean and the Norwegian Sea. The early stages of a typical storm development are characterized by a relatively concentrated microseismic source area to the west of NORSAR, whereas later on the source area expands and new sources appear to the NW and to the north of NORSAR. Simultaneously the spectral peaks migrate towards higher frequencies. Prepared in cooperation with Oulu Univ. (Finland). Dept. of Geophysics, and Helsinki Univ. (Finland). Inst. of Seismology. |
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