The compound Mocho-Choshuenco volcano is composed of twin glacier-covered stratovolcanoes, located east of Lago Rinihué and SE of Lago Panguipulli and post-dating a 4-km-wide basaltic caldera.  The small 2415-m-high Choshuenco stratovolcano, constructed on the NW rim of the caldera, is late-glacial in age.  A major plinian eruption produced the Neltume Pumice about 10,300 years ago.  The larger andesitic-to-dacitic, 2422-m-high  El Mocho volcano, constructed within the caldera, is postglacial and has been historically active.  Parasitic craters and basaltic scoria cones are located on the flanks of Mocho-Choshuenco, primarily on the NE and SW sides.  Two historical eruptions have been reported, one in 1864 and the other in 1937.