HR: 15:10h
AN: V23E-07    [Abstracts]
TI: Numerical Model of Large Bubble Bursts at Erebus Volcano, Antarctica
AU: * Morrissey, M
EM: mmorriss@mines.edu
AF: Colorado School of Mines - GGE, 1500 Illinois, Golden, CO 80401,
AU: Weaver, R
EM: rpw@lanl.gov
AF: Los Alamos National Laboratory, MS T087, Los Alamos, NM 87545,
AU: Gittings, M
EM: gittings@lanl.gov
AF: Los Alamos National Laboratory, MS T087, Los Alamos, NM 87545,
AU: Johnson, J
EM: jeff.johnson@ees.nmt.edu
AF: New Mexico Technological University, EES, Socorro, NM 87801,
AU: Jones, K
EM: kyle.jones@ees.nmt.edu
AF: New Mexico Technological University, EES, Socorro, NM 87801,
AB: Erebus volcano in Antarctica has been explosively degassing from its active phonolitic lava lake for decades. For at least the past three decades a lava lake has been present in the northeast corner of the inner crater. The lava lake continually convects and large bubbles burst at the surface 2-6 events per day. A geophysical network consisting a video coverage, acoustic sensors and broadband seismometers have been monitoring activity at the lava lake for years. There is remarkable correlation between bubble burst captured on video and infrasonic signals (with maximum excess pressure as much as 100 Pa) recorded on pressure sensors located within 300 m to 800 m from the active lake. Studies of 358 lava lake infrasound sources recorded over a 98 day period in 2006 suggest that bubble rupture location on the surface is distributed over a 40 m by 50 m area of the lava lake. Many of these bubbles are at least 10 m in diameter at rupture. The size and pressurization of the bubble bursts govern the force imparted to the atmosphere and therefore the characteristic features of the infrasonic pressure transients. A series of numerical simulations of bubble bursts from the lava lake at Erebus are performed in which bubble volumes, internal pressure and lava lake temperature are variables. The simulations are conducted with the computer code Sage that is a multi-material, finite-difference code with an adaptive mesh algorithm. Conductive heat transfer (power law temperature dependence), and strength model for wall rock and lava lake crust are considered. The locations of bubble bursts are constrained from mapped locations of bubble bursts recorded in 2006. We present results from these calculations and demonstrate the effects of bubble volume (5-10 m radius), internal pressure (0.5-10 MPa), lava lake temperature (800-1000C) and source location on the infrasonic signal.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting