Sector collapses like the one at Apacheta-Aguilucho have been observed on other volcanoes ( such as Mount St Helens during its 1980 eruption ) , and they result in characteristic landslide deposits known as debris avalanche deposits ; these feature hummock-like hills and often levees . Such collapses occur for different reasons for each event and are fairly common ; in the Central Andes alone 14 volcanoes feature deposits of such collapses . Such deposits commonly feature a stratigraphy that resembles that of the source edifice , as well as jigsaw-like cracks in rocks that form when rocks disintegrate during the collapse and sliding
1980 eruption
1980 eruption of Mount St. Helens
Apacheta-Aguilucho volcanic complex