Banahaw (also known as Banahao), the highest of a group of volcanoes south and east of Manila, is flanked by San Cristobal (7 km W) and Banahaw de Lucban on the NE. Andesitic-to-dacitic lava domes occur on the flanks of both Banahaw and San Cristobal. Deposits from two major Holocene debris avalanches from Banahaw extend 13 km NE and 26 km SE, where it forms 10 km of the coastline of Tayabas Bay. The youthfule morphology of the San Cristobal stratovolcano suggests that it postdates Banahaw. Banahaw de Lucban stratovolcano was constructed within the 8-km-wide amphitheater related to the two debris avalanches, and is the youngest volcano of the Banahaw complex. The 2-km-wide, 600-m-deep summit crater of Banahaw is open to the SSW and contained a crater lake until 1730, when it drained, forming mudflows. Mudflows were also recorded in 1743?, 1843 and 1909, possibly also associated with explosive activity.