HR: 1340h
AN: G53B-0883    [Abstracts]
TI: Recent Inflation of Kilauea Volcano During the Ongoing Eruption - Harbinger of Change?
AU: * Miklius, A
EM: asta@usgs.gov
AF: USGS, Hawaiian Volcano Observatory, Hawaii National Park, HI 96718 United States
AB: Since the start of the Pu`u `O`o-Kupaianaha eruption on Kilauea's east rift zone in 1983, the volcano's summit has subsided over 1.5 m. Over the last two years, however, leveling and GPS networks have recorded substantial inflation of the summit magma system. Since late 2003, the summit has extended almost 20 cm and risen about 5 cm. Leveling surveys suggest that the locus of inflation has been variable, with maximum uplift shifting from an area in the caldera near Halemaumau to an area in the southeastern part of the caldera, near Keanakako`i crater. Inflation rates have also been highly variable. Starting in mid-January 2005, the inflation rate accelerated for approximately a month, with extension rates across the summit reaching over 60 cm/yr. During this accelerated inflation, on January 25, a brief inflation-deflation transient was recorded on the tiltmeter network, accompanied by volcanic tremor. This event was followed by rapid slip of Kilauea's south flank, raising intriguing possibilities about the relationship between the magmatic system and the rapid slip events. Tiltmeters at the eruption site also recorded inflation, but only until early February, when a deflationary trend began, accompanied by increased eruptive output. The summit continued to inflate until late February, deflated slightly, then resumed inflation in April. These observations suggest that the high inflation rate in January-February was a result of increased magma supply to the summit magma system. In contrast, the most recent previous episode of inflation in 2002 was related to decreased outflow at the eruption site, effectively backing up pressure in the system. That inflation episode ended with the opening of new vents on the flank of Pu`u `O`o that produced high volumes of lava. The two previous, prolonged periods of uplift at the summit were in 1985-1986, before the eruption moved downrift from Pu`u `O`o to Kupaianaha, and 1990-1992, when eruptive activity shifted back to Pu`u `O`o. The current inflation of Kilauea is likely a combination of decreased efficiency of the transport system from the summit to the eruption site and an increase in magma supply. Past behavior of the volcano suggests that such conditions favor a shift in the location of the eruptive vent.
DE: 1243 Space geodetic surveys
DE: 8419 Volcano monitoring (7280)
DE: 8434 Magma migration and fragmentation
SC: Geodesy [G]
MN: Fall Meeting 2005