Global Volcanism Program | Image GVP-01824
The upper slopes of the symmetrical Mayon are exceptionally steep, averaging 35-40 degrees. They are covered with solidified lava agglutinate, the molten ejecta of lava fountains. This 1984 photo from the WSW shows a 250-m-deep, 3-km-long gully in the shadow at the right that was eroded by pyroclastic flows during the 1984 eruption.
Photo by Chris Newhall, 1984 (U.S. Geological Survey).