DETECTION OF A NEW SUMMIT CRATER ON BEZYMIANNY VOLCANO LAVA DOME: SATELLITE AND FIELD-BASED THERMAL DATA

Abstract

An explosive eruption occurred at the summit ofBezymianny volcano (Kamchatka Peninsula, Russia) on 11January 2005 which was initially detected from seismicobservations by the Kamchatka Volcanic Eruption Re-sponse Team (KVERT). This prompted the acquisition of17 Advanced Spaceborne Thermal Emission and ReflectionRadiometer (ASTER) satellite images of the volcano overthe following 10 months. Visible and infrared data fromASTER revealed significant changes to the morphology ofthe summit lava dome, later seen with field based thermalinfrared (TIR) camera surveys in August 2005. Themorphology of the summit lava dome was observed tohave changed from previous year’s observations andhistorical accounts. In August 2005 the dome contained anew crater and two small lava lobes. Stepped scarps withinthe new summit crater suggest a partial collapse mechanismof formation, rather than a purely explosive origin. Hotpyroclastic deposits were also observed to have pooled inthe moat between the current lava dome and the 1956 craterwall. The visual and thermal data revealed a complexeruption sequence of explosion(s), viscous lava extrusion,and finally the formation of the collapse crater. Based onthis sequence, the conduit could have become blocked/pressurized, which could signify the start of a new behav-ioural phase for the volcano and lead to the potential oflarger eruptions in the future.