"Old Ticsani" is a compound volcano that underwent a large collapse in the past and shed 15–30 cubic kilometres (3.6–7.2 cu mi) of mass down the Rio Tambo valley.

In southern Peru the Central Volcanic Zone includes the volcanoes Solimana, Coropuna, Ampato, Sabancaya, Chachani, El Misti, Ubinas, Huaynaputina, Ticsani, Tutupaca, Calientes, Yucamane, Purupuruni and Casiri.

[7] The volcanoes of Peru were active in the Plio-Quaternary and produced mainly calc-alkaline magmas such as andesite although more silicic rocks also occur.

[8] Ticsani features three lava domes, which were generated by latest Pleistocene and Holocene activity;[9] two of which are located within or at the margins of craters.

Pyroclastic flow deposits, generated during the collapse and growth of the lava domes, fill shallow valleys on the eastern flank.

[11] An earlier compound volcano is today preserved as a 3 kilometres (1.9 mi) long arcuate ridge,[9] which is northeast of the northernmost dome and opens to the west.

[3] This earlier volcano ("old Ticsani") crops out over an area of 65 square kilometres (25 sq mi) and consists of ignimbrites, lava flows, volcaniclastic deposits and debris from a large sector collapse;[11] a cryptodome is exposed within the arcuate ridge.

It is covered by the Mesozoic Yura Group and Matalaque Formation (sedimentary and volcanic rocks, respectively) which are exposed at the Rio Tambo.

[16] Phenocrysts found in the later eruption products include amphibole, biotite, feldspar, plagioclase, pyroxene and quartz.

[27] In 2005, earthquake activity was noted beneath Ticsani, possibly related to a hydrothermal system,[12] which raised alarm and concern among the local population.

[32] About 5,000 people live within 15 kilometres (9.3 mi) to Ticsani and would be threatened in the case of a future eruption, with particular hazards including ash fall, lahars, pyroclastic flows and the collapse of lava domes.

Volcanic gases may accumulate in valleys and depressions, while lava flows are unlikely to reach large distances and are thus minor threats.