HR: 1400h
AN: V43A-09    [Abstracts]
TI: Integration of video and infrasound to understand source locations and vent geometry at Erebus Volcano, Antarctica
AU: Jones, K R
EM: indy@nmt.edu
AF: New Mexico Tech, EES Department 801 Leroy Place, Socorro, NM 87801, United States
AU: Aster, R C
EM: aster@ees.nmt.edu
AF: New Mexico Tech, EES Department 801 Leroy Place, Socorro, NM 87801, United States
AU: * Johnson, J B
EM: jeff.johnson@unh.edu
AF: New Mexico Tech, EES Department 801 Leroy Place, Socorro, NM 87801, United States
AU: Kyle, P R
EM: kyle@nmt.edu
AF: New Mexico Tech, EES Department 801 Leroy Place, Socorro, NM 87801, United States
AU: McIntosh, W C
EM: mcintosh@nmt.edu
AF: New Mexico Tech, EES Department 801 Leroy Place, Socorro, NM 87801, United States
AB: Infrasound monitoring at Erebus volcano has enabled us to quantify eruption energetics and precisely determine the source location of Strombolian eruptions. Since January 2006 we have operated a three-element network of identical infrasound pressure transducers, to track explosive eruptions, triangulate source locations of the eruptions, and distinguish activity from several vents with diverse activities. In December 2006 the network was expanded to six identical pressure transducers with improved azimuthal distribution sited ~300 m to 700 m from the erupting vents. These sensors have a dynamic range of +/-125 Pa and are able to record non-distorted waveforms for almost all eruptive events. Since January 2006, eruptions have been identified from locations within the ~40 m diameter phonolitic lava lake, an adjacent smaller "active vent", and a vent ~80 m distant from the lava lake known as "Werner's". Since late 2005 until the end of 2006, activity was considerably elevated at the "lava lake", from which frequent (up to six per day) explosions were noted. These events entailed gas bubble bursts, some of which were capable of ejecting bombs more than 1 km distant and producing infrasonic transients in excess of 100 Pa at a distance of 700 m. Activity from "Werner's" vent was much more subdued in terms of eruptive frequency and the radiated acoustic energy, with all signals less than about 5 Pa at 700 m. Activity from the "active vent" was also observed, though notably, these acoustic transients were extended in duration in terms of time (> 5 s to more than 30 s), which reflects extended duration ash-venting source mechanisms, corroborated by video records. The updated infrasound network has operated through a relative lull in eruptive intensity (November - December 2006 - January 2007). Since January 2007 more frequent and larger explosions from the lava lake have been observed and recorded with infrasound and video. We quantify this recent upsurge in lava lake activity and present speculative mechanisms to account for the variable eruptive behavior of Erebus lava lake.
UR: http:erebus.nmt.edu
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
DE: 8439 Physics and chemistry of magma bodies
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly