The area hosts several relatively low-lying eruptive centers and domes of Early to Late Pleistocene age, namely Mt. Bintacan, Mt. Tabon-Tabon, Mt. Sisigon, Mt. Malobago, Mt. Calomoutan and Mt. Sujac.
All are older than the presently active Bulusan Volcano located in the northeast. There are reported hotsprings and altered grounds in the area which could enhance its geothermal prospectivity.
The currently active Bulusan volcanic vent is about 6 kilometers from the contract area. It is part of the Bicol volcanic arch which comprises at least 12 volcanic vents and complexes and is one of the 3 historically active centers of the arc (the other 2 being Mayon and Iriga).
