Volcan Láscar 5,641 m, is the most active volcano in the central Andes. Since 1988 a silicic lava dome has been growing in the summit crater, and there have been several recent eruptions, notably on April 19 and 20, 1993, when pyroclastic flows were erupted on both southern and northern flanks, and ash fell out as far distant as Buenos Aires, Argentina. The volcano consists of elongate series of six overlapping craters, trending roughly northeast, with the active, fuming crater located near the center of this cluster. It is about 800 m in diameter and 300 m deep. Grey pumice deposits from the 1993 eruption are visible in this photo, and the margins of some pyroclastic flows can be seen at right center. Most impressive, however, are the older, massive andesitic lava flows, exhibiting flow margins tens of meters high, well developed flow levées and transverse ogive ridges. (Section 7.4,Fig. 9.17; 9.18).

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