Spectral Properties and Source Areas of Storm Microseisms at NORSAR

• Main Authors: Korhonen, H, Pirhonen, S E
• Other Authors: ROYAL NORWEGIAN COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH KJELLER
• Format: Text
• Language: English
• Published: 1976
• Subjects: Seismology; Seismic Detection and Detectors; *MICROSEISMS; *SEISMIC DATA; *SEISMIC DETECTION; ESTIMATES; HIGH FREQUENCY; METEOROLOGICAL DATA; NORTH ATLANTIC OCEAN; NORWAY; NORWEGIAN SEA; POWER SPECTRA; SEISMOMETERS; SOURCES; SPECTRUM ANALYSIS; STORMS; VERY HIGH FREQUENCY; NORWEGIAN SEISMIC ARRAY; LONG PERIOD SEISMOMETERS; Norway; Norwegian Sea; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA021450; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA021450

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.