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Large-scale magnetic field perturbation arising from the 18 May 1980 eruption from Mount St. Helens, Washington

Physics of the Earth and Planetary Interiors

By:
and
DOI: 10.1016/0031-9201(89)90209-4

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Abstract

A traveling magnetic field disturbance generated by the 18 may 1980 eruption of Mount St. Helens at 1532 UT was detected on an 800-km linear array of recording magnetometers installed along the San Andreas fault system in California, from San Francisco to the Salton Sea. Arrival times of the disturbance field, from the most northern of these 24 magnetometers (996 km south of the volcano) to the most southern (1493 km S23?? E), are consistent with the generation of a traveling ionospheric disturbance stimulated by the blast pressure wave in the atmosphere. The first arrivals at the north and the south ends of the array occurred at 26 and 48 min, respectively, after the initial eruption. Apparent average wave velocity through the array is 309 ?? 14 m s-1 but may have approached 600 m s-1 close to the volcano. The horizontal phase and the group velocity of ??? 300 m s-1 at periods of 70-80 min, and the attenuation with distance, strongly suggest that the magnetic field perturbations at distances of 1000-1500 km are caused by gravity mode acoustic-gravity waves propagating at F-region heights in the ionosphere. ?? 1989.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Large-scale magnetic field perturbation arising from the 18 May 1980 eruption from Mount St. Helens, Washington
Series title:
Physics of the Earth and Planetary Interiors
DOI:
10.1016/0031-9201(89)90209-4
Volume
57
Issue:
1-2
Year Published:
1989
Language:
English
Publisher:
Elsevier
Publisher location:
Amsterdam, Netherlands
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Physics of the Earth and Planetary Interiors
First page:
23
Last page:
31