Scars at elevations of on the edifice have been the origin of mudflows; the largest is known as Estación flow and covers much of the southern and western foot of San Pedro to distances of ; the debris apron reaches the Loa River and San Pedro River. These mudflows occurred between 110,000 - 36,000 years ago and they filled the river bed of the Loa, while the impact on the San Pedro River was much more minor. Hot avalanche deposits or pyroclastic flows are also found on the volcano; the largest of which covers large parts of the edifice and has a total volume of approximately . These deposits contain prismatic jointed blocks and poorly sorted pumice, with their thickness ranging from a thick layer to scattered rocks. Their formation was probably due to the steep incline of San Pedro's slopes which tended to destabilize lava bodies high on the edifice, similar to regular landslides. At least one Plinian fall deposit is known from San Pedro; the size of the deposit indicates that it was as large as the AD 79 eruption of Vesuvius in Italy. This Plinian eruption was accompanied by the formation of an ignimbrite that covers much of the southern, southwestern and western slopes of San Pedro and reaches thicknesses of . It has a volume of and is called the El Encanto ignimbrite.