Structural setting of the Bicol Basin and kinematic analysis of fractures on Mayon Volcano, Philippines

Mayon Volcano is located within the Bicol Basin in the southeastern region of Luzon, Philippines. The basin is contained within a releasing bend associated with the curvature of the central segment of the left-lateral Philippine Fault. A structural analysis of the faults that traverse the Bicol Basin was conducted through reviews of existing literature, seismic data interpretation, and remote sensing; in particular, those structures that may have influenced the growth and evolution of Mayon. Dynamic analysis of the aforementioned structures reveals a regional transtensional stress regime for the Bicol Basin. Field investigation on Mayon's slopes revealed the existence of fractures along its western and eastern flanks. These structures on Mayon have the same geometry as the dominant faults found within the Bicol Basin. Interpretation of these fractures indicates a tectonic control over their origin. The identification of fractures on Mayon's slopes is the first description of such features on its edifice. These new data highlight the probable landslide hazards associated with an oversteepened volcano that may have been further destabilized by tectonic activity.