Continuous gravity measurements from Kilauea Volcano Hawai'i, 2007-2008
Abstract
We present more than a year of continuous 1 Hz gravity data collected in an underground vault near the US Geological Survey Hawai'i Volcano Observatory. The data were collected with a LaCoste and Romberg D- meter streaming to a digitizer with a GPS clock. The instrument was installed in February 2007, and has been collecting data continuously since that time, except for periods when the instrument went off scale due to drift or local earthquakes with magnitudes of about M4.0+. This is one of the few installations of a continuous gravity meter at an active volcano and has the potential to provide important new constraints on the physical system of volcanoes. The most significant observation in the time series is a sizable gravity increase during rapid summit inflation at Kilauea in June-July 2007. The inflation was a consequence of refilling of the summit magma reservoir following an intrusion and formation of a new eruptive vent on the volcano's east rift zone during June 17-19, 2007. Uplift should result in a gravity decrease as the instrument moves farther from the center of the Earth, therefore the measured gravity increase during inflation suggests that mass was being added to the summit magma reservoir. Inflation continued until July 21, 2007, when a reorganization of the east rift zone magma plumbing system led to the formation of a new long term eruptive vent and a period of sustained summit deflation. The gravity meter is also an effective low frequency (less than 0.5 Hz) seismometer and we present comparisons of the gravity record with a broadband seismometer. In addition to observing previously identified low frequency (0.004 to 0.5 Hz) events associated with known volcanic activities and sources in the Kilauea summit area, we also recognize previously undetected low frequency events associated with high-frequency earthquakes outside of the Kilauea summit area. We provide a preliminary interpretation of these observations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.V11B2019T
- Keywords:
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- 1217 Time variable gravity (7223;
- 7230);
- 8419 Volcano monitoring (7280)