Mount Hasan throughout its activity; this activity has been dated to 120,000, 65,000 and the most recent event 34,000 years ago. This volcanism however is not part of the actual Mount Hasan system. The main edifice has produced about of magma every millennium. is the oldest (13 million years) volcanic structure, it is among the oldest volcanoes of the Central Anatolian volcanic province. This volcano is a small sized volcano with a caldera which crops out on the southwestern side of Mount Hasan. It grew over sediments to a present-day elevation of ; today it is eroded, partly buried by the younger Hasan volcanics and disrupted by strike-slip faulting. About 7 million years ago the Paleovolcano began to grow north of ; it too is buried by more recent volcanics but part of its deposits crop out on the northwestern flank of Mount Hasan in the form of ignimbrites, lahars and lava flows. The Paleovolcano also formed a caldera which produced the rhyolitic Dikmen-Taspinar Ignimbrites; formerly the Cappadocian tuffs were in general attributed to volcanism at Mount Hasan, Mount Erciyes and Göllü Dag. The Quaternary activity gave rise to the Mesovolcano and Neovolcano, with the former centered between the two present-day summits. This volcano produced ignimbrites, lava domes and lava flows and eventually a caldera; it too has been dissected by faulting which probably also influenced the development of the volcano and its activity probably occurred between 1 and 0.15 million years ago. Finally, the Neovolcano grew within the caldera, producing various kinds of deposits; these include lava domes with accompanying pyroclastic flow deposits, breccia in the rim of the Mesovolcano caldera that probably formed through the interaction of intruding magma with water in the caldera, 700,000 years ago rhyolitic flows and ignimbrites accompanied by the formation of another, caldera, and finally andesitic lava flows and lava domes which form the two main summits. Small Mount Hasan is probably older as it is more heavily eroded while the morphology of Big Hasan Dagi is fresher although its pyroclastic flow deposits are heavily incised. Dates of 33,000 and 29,000 years ago have been obtained on the summit domes and ages of 66,000±7,000 years on the most recent monogenetic volcano south of Mount Hasan. Tephras found in the Konya plain and in a lake of the Turkish Lakes Region have been attributed to Mount Hasan. The debris flow from Mount Hasan occurred