Geophysical Research Letters

Temporal gravity and height changes of the Yellowstone Caldera, 1977–1994

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Abstract

This paper describes the longest record of gravity measurements in the area of the Yellowstone caldera, Wyoming. The temporal gravity changes, at the ±12 µGal (10−8 ms−2) precision level, are compared with changes in heights from leveling and GPS. The gravity field decreased across the caldera from 1977 to 1983 during the uplift and attained a maximum decrease of up to −60± 2 µGal along the Caldera axis. The gravity field then reversed polarity to increasing values, of up to 60±12 µGal between 1986 and 1993. The ratio between height and gravity changes varied during the entire time, but converged over the latter period following the free-air gravity gradient. General ground deformation deduced from leveling showed caldera-wide uplift of ∼15 mm/a during the period of gravity decrease, then from leveling and GPS, subsidence of ∼25 mm/a during the gravity increase.

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