Anatomy of a Volcanic Cone Traversed by a Strike-Slip Fault: An Example from Ancestral Mount Bao, Leyte, Philippines

Abstract

Ancestral Mount Bao (AMB) is an eroded stratovolcano in Leyfe, Philippines, directly overlying and offset by the active le??-lateral Philippine fault. This volcano was investigated to determine the deformation characteristics of a volcano traversed by a strike-slip fault. The deformation features recognized in the A MB include: a summit graben, sigmoidal surface features, cone elongation, normal faults, and reverse faults. Pronounced erosion is evident in the north-north west and south-southeast flanks, regions of the AMB volcano above the Philippine fault. On these highly eroded volcanic flanks are widespread landslide deposits. The identified structures and related deformational features were compared with previous analogue sand cone models of volcanoes on top of strikeslip faults, models that describe a unique pattern of structural deformation. These features identified in the field and in satellite imagery of the AMB are identical to all the structures found in the analogue sand cone models.