REMOTE MAPPING OF LAVA VESICULARITY AT MEDICINE LAKE VOLCANO (CA) USING MODIS/ASTER AIRBORNE SIMULATOR DATA

The growth and collapse of silicic lava domes has resulted in thousands of deaths over the last century. Surface vesicularity of silicic lava is correlated with the collapse of lava domes which trigger pyroclastic activity. The ability to remotely monitor vesicularity of active silicic lava domes is valuable because areas exhibiting coarsely vesicular pumice on active domes present the greatest volcanic hazard.

We used thermal infrared (TIR) data from the MODIS/ASTER (MASTER) Simulator flown over Medicine Lake Volcano (MLV) in northernmost California to map lava vesicularity. We focused on Little Glass Mountain (ca. 900) as a test site because of its unvegetated silicic lavas. While this particular flow is chemical uniform, it exhibits textural (vesicularity) variation, and has TIR ground-truth data available from previous studies.

Emissivity variations between obsidian and vesicular pumice were used to map lava texture. The abundance and geometry of vesicles accounts for the three types of texture and are most readily observed in emissivity spectra at 9.2 microns. The most vesicular parts of Little Glass Mountain occur adjacent to the southern edge of the flow and along the northwest sector. Were this an actively forming silicic dome on a stratovolcano, areas beneath these regions would be at greatest risk form sector collapse. Our results are consistent with those from previous research using other sensors with ground-truth data and reinforce the utility of remotely sensed data to mitigate volcanic hazards.