It consists of various volcanic deposits, including several calderas, and its activity has been related to the presence of several faults in the area and to regional tectonics.

Activity began in the Miocene and continued into the Holocene; a mural found in the archeological site of Çatalhöyük has been controversially interpreted as showing a volcanic eruption or even a primitive map.

[26] Cinder cones, maars and accompanying lava flows also occur around Mount Hasan, they are part of a basaltic volcano family[27] that forms parasitic vents.

[23] These include the Yıpraktepe cone/maar[28] and a lava flow field at Karataş which covers an area of 60 square kilometres (23 sq mi) and was produced by fissure vents.

[39] The westerly Mount Hasan, central Keçiboyduran[40] and easterly Melendiz Dağ[41] form the Niğde Volcanic Complex,[42] a mountain range, which is surrounded by plains and whose summits reach heights of over 3,000 metres (9,800 ft).

Of these mountains, Melendiz Dağ is more heavily eroded compared to the steep cones of Hasan[43] and like Keçiboyduran is of early Pliocene age.

[45] It and to some degree Mount Hasan are also surrounded by a large depression,[46] and the volcanoes of this alignment are separated by faults.

[13] The basement in Central Anatolia is formed by magmatic, metamorphic and ophiolitic rocks, the former of which are of Paleozoic to Mesozoic age;[33] it crops out at scattered sites and in the Kirshehir and Nigde massifs.

[37] The surface however consists mainly of Tertiary volcanic rocks,[48] which are formed both by numerous ignimbrites,[17] volcaniclastic material and individual volcanoes.

[15] Mount Hasan has produced volcanic rocks with compositions ranging from basalt to rhyolite but the dominant components are andesite and dacite[49] which define an older tholeiitic and a younger calc-alkaline[50] or alkaline suite.

[34] These rocks in turn include amphibole, apatite, biotite, clinopyroxene,[51] garnet,[52] ilmenite, mica,[51] olivine,[53] orthopyroxene, plagioclase,[54] pyroxene[22] in the form of augite, bronzite, diopside, hypersthene and salite,[55] and quartz.

[60] Evidence of fractional crystallization has been encountered in the most recent stage rocks[53] and more generally plays a role in the genesis of Hasan magmas[61] although it does not explain all of the compositional traits.

[63] Older volcanic stages also show evidence of subduction influence[64] while the more recent magmas are more indicative of intraplate processes,[65] the effects of crustal extension[66] and of the presence of water.

[73] Between October/November and May, the mountain is frequently covered by snow due to the common precipitation at that time and when it melts the water mostly infiltrates into the permeable rocks,[74] making the volcano a principal groundwater recharge area in the region.

[75] Additionally, volcanics of Mount Hasan form a major aquifer[76] and the Melendiz River passes north and northeast of the volcano.

It grew over sediments to a present-day elevation of 1,700 metres (5,600 ft); today it is eroded, partly buried by the younger Hasan volcanics[22] and disrupted by strike-slip faulting.

About 7 million years ago the Paleovolcano began to grow north of Keçikalesi; 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.

[16] A major Plinian to sub-Plinian pumice-forming eruption took place 417,200 ± 20,500 years ago, forming the Belbaşhanı Pumice[84] and deposited fallout over much of Central Anatolia.

[103] Future activity at Hasan could impact neighbouring villages, and larger eruptions might disrupt air traffic and tourism in Cappadocia.

[110] The discovery of this mural has drawn attention to the volcano[111] and has led to efforts to date the eruptive activity of Mount Hasan.