There is evidence in the collapse deposit that a lava flow was being erupted on the volcano when the landslide occurred, which together with the presence of pyroclastic fallout on the southwestern side of Socompa implies the collapse may have been started by volcanic activity. The quantity of water in the edifice rocks on the other hand was probably minor. Another theory assumes that the volcanic edifice was destabilized by ductile and mechanically weak layers beneath Socompa; under the weight of the volcano these layers can deform and flow outward from the edifice, causing the formation of thrusts at its foot. Evidence of such spreading of the basement under Socompa has been found.