At most 600,000 years old, Kīlauea is still quite young for a Hawaiian volcano; the oldest volcano on the island, the northwestern Kohala, experienced almost 900,000 years of activity before going extinct. The volcano's foreseeable future activity will likely be much like it has been for the past 50,000 to 100,000 years; Hawaiian and explosive activity will make Kīlauea taller, build up its rift zones, and fill and refill its summit caldera.