HR: 08:15h
AN: V51H-02    [Abstracts]
TI: Seismic Characterization of the June 17, 2007 East Rift Intrusion at Kilauea Volcano
AU: * Wilson, D C
EM: dwilson@usgs.gov
AF: USGS Hawaiian Volcano Observatory, Bldg. 336 Crater Rim Drive, Hawaii National Park, HI 96718, United States
AU: Uribe, J
EM: juribe@usgs.gov
AF: USGS Hawaiian Volcano Observatory, Bldg. 336 Crater Rim Drive, Hawaii National Park, HI 96718, United States
AU: Kamibayashi, S
EM: sabraham@usgs.gov
AF: Center for the Study of Active Volcanoes, University of Hawaii at Hilo 200 West Kawili Street, Hilo, HI 96720, United States
AU: Nakata, J
EM: jnakata@usgs.gov
AF: USGS Hawaiian Volcano Observatory, Bldg. 336 Crater Rim Drive, Hawaii National Park, HI 96718, United States
AU: Okubo, P
EM: pokubo@usgs.gov
AF: USGS Hawaiian Volcano Observatory, Bldg. 336 Crater Rim Drive, Hawaii National Park, HI 96718, United States
AB: An early morning earthquake swarm on Sunday, June 17, 2007 signaled the beginning of a sequence of seismic and deformational activity consistent with an intrusion of magma in the upper East Rift of Kilauea volcano, Hawaii. This culminated in an outbreak of lava from a discontinuous 160 meter long fissure, approximately 6 km west of Pu`u `O`o and 13 km southeast of Kilauea's summit. Here we detail the seismic characteristics and observed deformation accompanying this magmatic intrusion and eruption. Seismic activity began at 0216 Hawaiian Standard Time (HST - UTC minus 10 hours) with 38 events greater than magnitude 2 and over 80 located earthquakes in the first two hours. These earthquakes were centered 1.5-2 km southwest of Mauna Ulu (9 km southeast of Kilauea summit) between 1.5 and 3 km deep. At the same time, tiltmeters at Kilauea's summit began indicating rapid deflation of the summit area. Starting at 0730 HST there was a pronounced eastward shift (by about 4 km) of the center of seismicity to a location just west of Makaopuhi crater. At this time GPS stations began to show extension across the rift in that area. Over the next 7-8 hours, the locus of seismicity continued to migrate eastward with over 70 events located at Makaopuhi crater. Over the next day more than 40 earthquakes occurred with locations ranging from the uppermost east rift to Makaopuhi crater. The next afternoon (June 18) there was another pronounced eastward shift in seismicity with 23 earthquakes, occurring between 1459-1600 HST, centered between Makaopuhi crater and Napau crater. Kilauea summit area tremor levels rose throughout the day on June 17, reaching a peak of 24 times background levels mid-day on the June 18, before beginning a slow decline. Tremor levels along the East Rift showed brief periods of strong activity (4-6 times background levels), and lava was discovered at the surface shortly after one such tremor episode at 0625 HST on June 19. Shortly before noon on the same day, Kilauea tiltmeters indicated an end to summit deflation, and GPS stations indicated a slowing of rift extension which had reached nearly 1 meter of across rift extension. This series of punctuated eastward migrations of seismicity (along with the observed deformational signals) provide a detailed record of the space-time evolution of the June 17 magmatic intrusion and eruption.
UR: http://hvo.wr.usgs.gov/
DE: 7280 Volcano seismology (8419)
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
DE: 8425 Effusive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting