Topographic map of San Pedro and the surrounding region.

20.2 Photograph and interpretive sketch view of Volcan San Pedro from the NW indicating the principal structural elements. A - Débris fan derived from San Pablo volcano; B - summit of the Old Cone capped by flat-lying andesite lavas exposed in the scarp of the collapse amphitheater; C and D - andesite and dacite flows of the Young Cone overlying lavas and volcaniclastics of the Old Cone; E - western crater of Young Cone; F - collapse scars in lavas on oversteepened flanks of Young Cone; G- apron of hot avalanche deposits originating from collapse of Young Cone lava flow fronts; H - eastern and younger inner crater of Young Cone with fumarole (From O' Callaghan and Francis, 1986).