The Quaternary Malindang volcano is located at the southern end of an eroded massif (Ampiro volcano is at the northern end), W of Iligan Bay in N-central Mindanao. Legends record a large eruption from the dominantly basaltic-to-andesitic volcano in the past, although no confirmed eruptions have been documented (Salise et al., 1991). Reports of increased activity in 1991 at the time of tectonic earthquakes prompted widespread evacuations, and although an eruption did not occur, a previously unknown geothermal area was discovered.