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Azimuth Estimations From a Small Aperture Infrasonic Array: Test Observations at Stromboli Volcano, Italy
Author(s) -
Yamakawa Kazuya,
Ichihara Mie,
Ishii Kyoka,
Aoyama Hiroshi,
Nishimura Takeshi,
Ripepe Maurizio
Publication year - 2018
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 - 10.1029/2018gl078851
Subject(s) - capon , geology , volcano , beamforming , seismology , infrasound , azimuth , aperture (computer memory) , strombolian eruption , remote sensing , acoustics , computer science , magma , telecommunications , physics , optics
We tested the performance of an infrasonic array consisting of three microphones with a 20‐m aperture at Stromboli volcano, Italy. There were four active vents separated by ∼10 ∘ . We employed multiple signal classification (MUSIC) to estimate direction of arrival (DOA) of the detected signals. Using test signals of which the source vents were identified by visual observation, the resolution of DOA estimation of MUSIC is compared with those of Capon beamforming, grid search, and semblance. We confirmed that MUSIC and grid search gave better resolution of DOA than the other two methods. Also, MUSIC provided the best resolutions in time and frequency. It was shown that the DOA switched between different vents or fluctuated in short time scales and can vary with frequency, which indicate multiple active sources. Possible DOA estimation errors were evaluated. A small aperture infrasonic array combined with MUSIC will become a powerful tool for studying and monitoring active volcanoes.