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Infrasonic tremor in the diffraction zone
Author(s) -
Fee David,
Garcés Milton
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl030616
Subject(s) - infrasound , amplitude , geology , volcano , seismology , daytime , impact crater , wind speed , geophysics , acoustics , physics , atmospheric sciences , optics , oceanography , astronomy
Volcanic tremor signals recorded by an infrasound array ∼12.5 km from the active vent of Kīlauea Volcano show clear diurnal amplitude variations and originate from a well defined direction pointing to the active Pu`u `Ō`ō crater complex. Spectral amplitudes between 0.02–0.3 Hz, a proxy for wind speed, increase when the wind speeds increase during the daytime. Spectral amplitudes between 0.5–3 Hz, where infrasonic tremor is concentrated, increase when the wind speeds decrease at night. Power spectrum analysis shows that when ambient noise levels drop, infrasonic tremor amplitudes rise. Array processing confirms this relationship and reveals tremor detections and amplitudes decrease during the day. These changes in infrasonic tremor spectral amplitude and coherence are most likely due to diurnal variations in atmospheric boundary layers affecting infrasonic propagation within the diffraction zone. Recognition of these regional atmospheric patterns is necessary to permit robust infrasonic remote sensing of volcanic processes.