Paper No. 6
Presentation Time: 2:45 PM
TERRESTRIAL LASER SCANNING (TLS) OBSERVATIONS OF THE PHONOLITE LAVA LAKE AT EREBUS VOLCANO, ANTARCTICA
JONES, Laura K.Z.1, FRECHETTE, Jedediah D.
2, OKAL, Marianna
3, KYLE, Philip
1 and OPPENHEIMER, Clive
4, (1)Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, NM 87801, (2)Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, (3)UNAVCO, 6350 Nautilus Drive, Boulder, CO 80301, (4)Department of Geography, University of Cambridge, Downing Place, Cambridge, CB2 3EN, United Kingdom, lkzjones@gmail.com
Terrestrial Laser Scanning (TLS) observations were made in December 2008 and 2009 of the persistent convecting phonolite lava lake in the summit crater of Erebus volcano, Antarctica. Oppenheimer et al. (2009,
Earth and Planetary Science Letters 284: 392-398) have documented cyclic behavior of gas emissions, thermal fluxes, and surface velocities of the lake. The characteristics of these newly discovered cycles are under investigation but are undoubtedly related to the degassing behavior of the conduit that feeds the lake. The goal of this study was to quantify changes in the lava lake surface elevation and to compare these results to ongoing gas, thermal and seismic studies. The lava lake represents the exposed top of a shallow, convecting magmatic conduit and for this reason the TLS data should provide insight into the lower (unseen) magmatic system.
In December 2008, TLS was used to continuously image the lake for 4 hours at approximately 1 minute intervals and in 2009 the lake was imaged for 8 hours at approximately 30 second intervals. Fluctuating plume gases led to highly variable visibility throughout the scan window. Therefore, spatial averaging over multiple domains was used to reduce the point cloud to a one-dimensional elevation time series. Analysis of this time series revealed approximately 18-minute cycles during which the lava lake surface would rise and fall 1-2 meters. These cycles remained generally constant during the entirety of the scans, except for a period of quiescence during the first hour of the 2009 scans. These continuous high-resolution TLS scans coupled with GPS timing were able to offer an unprecedented view into the short-term evolutions of the lava lake surface.
