オリサバ山

Pico de Orizaba (Volcán Citlaltépetl), México's highest peak and North America's highest volcano, lies at the southern end of a volcanic chain extending north to Cofre de Perote volcano, east of the Serdan-Oriental Basin. The edifice was formed in three stages beginning during the mid-Pleistocene. Construction of the initial Torrecillas and Espolón de Oro volcanoes was contemporaneous with growth of Sierra Negra volcano on the SW flank, and was followed by edifice collapses that produced voluminous debris avalanches and lahars. The modern volcano was constructed during the late Pleistocene and Holocene of viscous andesitic and dacitic lavas, forming the current steep-sided cone. Repetitive explosive eruptions beginning during the early Holocene accompanied lava dome growth and lava effusion. Recorded eruptions have consisted of moderate explosive activity and the effusion of dacitic lava flows. The last known observations of activity were in 1846 CE.