Figure 10

Detecting new fissure eruptions around Pu‘u ‘Ō‘ō. On August 3, 2011, the WTcam observed the opening of new fissures on the lower west flank of Pu‘u ‘Ō‘ō, which drained the lava lake within the crater. Just minutes prior to the fissure opening, the camera captured the uplift of a portion of the west flank (a-b, about 3 m vertical movement in this image; 10 m uplift was observed elsewhere, out of this view, with other webcams). The uplift presumably resulted from a dike or sill propagating through the flank. Over a span of just four minutes, the surge of lava had traveled 600 m (c). The flow soon extended out of the field of view and entered the forest to the north (right side of image in d). On September 21, 2011, a new fissure opened on the upper east flank of Pu‘u ‘Ō‘ō cone. A direct view of the fissure was blocked by topography, but anomalous heating of the clouds and fog around the new vent was a clear indicator of the onset (e, f). The thermal images have not been corrected for atmospheric or volcanic gas effects, and actual surface temperatures may be higher than the apparent temperatures shown here.