This stratovolcano has a 4 kilometres (2.5 mi) wide caldera with eruptive centres on its northeastern and southwestern margins. These centres are aligned on a northeast-trending fracture that also includes a monogenetic centre 8 kilometres (5.0 mi) northeast of the caldera (GVP). The volcano has produced long lava flows, although the more proximal parts of the flow were later degraded by glaciation.[3] The volcano has been assigned a Holocene age given the young appearance of some of its eruption products.[4] The volcanism was at first dacitic and later changed to basaltic andesite (GVP).