Possible tectonomagnetic effect observed from mid-1989, to mid-1990, in Long Valley Caldera, California
Geophysical Research Letters
- By:
- R.J. Mueller , M.J.S. Johnston , and J.O. Langbein
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Abstract
Precise measurements of local magnetic fields have been obtained with a differentially connected array of three proton magnetometers in the Long Valley Caldera region since 1984. After correction for secular variation, it is apparent that an anomalous 2 nT decrease in the magnetic field occurred from mid-1989 to mid-1990 at the magnetometer located closed to the center of the resurgent dome inside the caldera. During this period a significant increase in geodetic strain rate of 8.5 ppm/a was observed on the two-color geodimeter network within the caldera from October, 1989, to mid-1990 and a dramatic increase in seismic activity occurred from December, 1989 to July, 1990. A simple dilatational point-source model with pressure increasing by 52 Mpa from October 1989 to August 1990 at a depth of about 7 km beneath the center of the resurgent dome can be fit to the strain data. Magnetic, seismic and geodetic data suggest that an episode of active magmatic intrusion occurred from late 1989 to mid-1990 at a depth of about 7-8 km beneath the resurgent dome within the caldera. -from AuthorsAdditional publication details
- Publication type:
- Article
- Publication Subtype:
- Journal Article
- Title:
- Possible tectonomagnetic effect observed from mid-1989, to mid-1990, in Long Valley Caldera, California
- Series title:
- Geophysical Research Letters
- Volume:
- 18
- Issue:
- 4
- Year Published:
- 1991
- Language:
- English
- Larger Work Type:
- Article
- Larger Work Subtype:
- Journal Article
- Larger Work Title:
- Geophysical Research Letters
- First page:
- 601
- Last page:
- 604