The forested Arayat volcano is one of the few topographic features that rise above the flat Central Plain of Luzon Island. Weak steaming occurs at the NW side of the summit, which rises NE of the city of Angeles. A large breached crater on the WNW side is the apparent source of a major debris-avalanche deposit that forms hummocky terrain beyond the W and NW sides of the volcano. Post-collapse activity formed an andesitic dome known as White Rock in the collapse amphitheater. There are no reports of historical eruptions. Although the volcano was listed as active during the past 2000 years (IAVCEI, 1973), perhaps referring to its thermal activity, the only dated rocks are 0.53 and 0.65 Ma basalts that predated collapse and formation of the lava dome.