Global Volcanism Program | Image GVP-07992
The three coalescing Cerro San Pedro lava domes (center), seen here from the NE, were constructed within the 7 x 10 km wide San Pedro caldera. The ridge at the left is the eastern rim of the caldera, which cuts andesitic-to-dacitic lava domes of early Pleistocene age. The dacitic San Pedro lava domes were dated at 0.75-0.80 million years and were constructed along a WNW-trending line. Two of the domes have partially collapsed, forming large debris-avalanche deposits that reach up to 10 km from the source.
Photo by Jim Luhr, 1978 (Smithsonian Institution).