Continuous Gravity and Tilt Reveal Anomalous Pressure and Density Changes Associated With Gas Pistoning Within the Summit Lava Lake of Kīlauea Volcano, Hawai'i. Issue 5 (14th March 2018)

• Record Type: Journal Article
• Authors: Poland, Michael P.; Carbone, Daniele
• Is Part Of: Geophysical research letters. Volume 45:Issue 5(2018)
• Page Start: 2319
• Page End: 2327
• Publication Date: 2018-03-14
• Subjects: Kilauea -- lava lake -- deformation -- gravity change -- pressure -- geodesy; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL076936
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Gas piston events within the summit eruptive vent of Kīlauea Volcano, Hawai'i, are characterized by increases in lava level and by decreases in seismic energy release, spattering, and degassing. During 2010–2011, gas piston events were especially well manifested, with lava level rises of tens of meters over the course of several hours, followed by a sudden drop to preevent levels. The changes in lava level were accompanied by directly proportional changes in gravity, but ground deformation determined from tilt was anticorrelative. The small magnitude of the gravity changes, compared to the large changes in volume within the vent during gas pistons, suggests that pistoning involves the accumulation of a very low‐density (100–200 kg/m 3 ) foam at the top of the lava column. Co‐event ground tilt indicates that rise in lava level is paradoxically associated with deflation (the opposite is usually true), which can be modeled as an increase in the gas content of the magma column between the source reservoir and the surface. Gas pistoning behavior is therefore associated with not only accumulation of a shallow magmatic foam but also more bubbles within the feeder conduit, probably due to the overall decrease in gas emissions from the lava lake during piston events. Key Points: Transient lava level changes due to gas pistoning at Kilauea's lava lake are driven by very low density (90% porosity) magmatic foams Deformation during gas pistons is anticorrelative with lava level, suggesting bubble accumulation in the magmatic conduit The joint analysis of deformation and gravity change is critical for understanding the dynamics of shallow magmatic activity