The 2158-m-high Banahaw (also known as Banahao) is the highest of a group of volcanoes south and east of Manila.  Banahaw is flanked by San Cristobal volcano on the west and Banahaw de Lucban on the NE.  Andesitic-to-dacitic lava domes occur on the flanks of Banahaw and San Cristobal.  Two major Holocene debris avalanches have occurred at Banahaw volcano.  The deposit from one extends 13 km to the NE and the other 26 km to the SE, where it forms 10 km of the coastline of Tayabas Bay.  San Cristobal stratovolcano rises to 1480 m, 7 km west of Banahaw.  Its youthful morphology suggests that it postdates Banahaw.  Banahaw de Lucban is a 1875-m-high stratovolcano that was constructed within the 8-km-wide, horseshoe-shaped caldera 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.