Remote monitoring of Mount Erebus volcano, Antarctica, using polar orbiters: Progress and prospects

Mount Erebus (Antarctica) is a remote and inhospitable volcano, where field campaigns are possible only during the austral summer. In addition to cont inuously monitoring seismic instruments and video cameras, data from scanne rs flown aboard polar orbiting space-craft, such as the Thematic Mapper (TM ) and Advanced Very High Resolution Radiometer (AVHRR), can contribute to c ontinuous, year-round monitoring of this volcano. Together these data allow measurement of the temperature of, thermal and gas flux from, and mass flu x to a persistently active lava lake at Erebus' summit. The monitoring pote ntial of such polar-orbiting instruments is enhanced by the poleward conver gence of sub-spacecraft ground-tracks at the Erebus latitudes, permitting m ore frequent return periods than at the equator. Ground-based observations show that the Erebus lava lake was active with an area of similar to 2800 m(2) and sulphur dioxide (SO2) flux of (230 +/- 90 ) t d(-1) prior to September 1984. AVHRR-based lake area and SO2 flux estim ates are in good agreement with these measurements, giving (2320 +/- 1200) m(2) and (190 +/- 100) t d(-1), respectively, during 1980. However during l ate-1984 the lava lake became buried, with TM data showing re-establishment of the lake, with a TM-derived surface temperature of 578-903 degrees C, b y January 1985. Following these events, ground-based lake area and SO2 flux measurements show that the lake area and SO2 flux was lower (180-630 m(2) and 9-91 t d(-1), respectively). This is matched by a decline in the AVHRR- and TM-derived rate of magma supply to the lake from 330 +/- 167 kg s(-1) prior to 1984 to 30-76 kg s(-1) thereafter. Clearly, a reduction in magma s upply to, and activity at, the lava lake occurred during 1984. We look forward to using data from such future polar-orbiting sensors as th e Moderate Resolution Imaging Spectrometer (MODIS), Advanced Spaceborne The rmal Emission and Reflectance Radiometer (ASTER), Enhanced Thematic Mapper (ETM+) and Advanced Along Track Scanning Radiometer (AASTR) to contribute t o high (> once a day) temporal resolution measurement and monitoring of act ivity at this volcano. Such analyses will in turn contribute to a more comp lete understanding of how this volcano works.