Visual Observations

Visual observations of the volcano are extremely important, both for monitoring escalating volcanic events as they develop, and also for tracking the growth of the lava dome over the long term. Several different techniques are used, including: visual observations and photography from the ground and from a helicopter; monitoring the activity with remote digital cameras; and topographic surveying of the lava dome by theodolite and photogrammetric methods in order to monitor its growth and estimate changes in volume over time, which in turn provide valuable information on rates of extrusion.