The cloud cover which normally obscures the top portions of the volcano recently cleared for a short period the evening of 5 May, allowing observation of incandescence, the glowing of rock.
The photograph shown was taken during an exceptionally clear period following rain. Incandescence occurs when material is at sufficiently high temperatures so that it emits visible light. For rock, this occurs at over 500 degrees Centigrade. Many of the bright spots seen in the photograph are related to fumaroles, the locations where hot gas comes out of the volcano. Only three of the spots shown on this photograph (the brightest three) are visible to the naked eye. Long exposure photography taken over a period of several minutes reveals these and the other points of incandescence.
The locations of the incandescent spots are the same as those that were first observed on 11 November 2010, which can be viewed here. Although no new incandescent spots have appeared, the continued incandescence at these locations indicates that there is still a significant source of heat from below. This observation supplements MVO’s other observations, which indicate that Soufriere Hills Volcano has not shut down and remains linked to the deep source region.