Mount Wrangell description and information

From Miller and others (1998): "Mount Wrangell is a large andesitic shield volcano with a volume of about 900 cubic kilometers (Nye, 1983). Its top is capped by a 4 by 6 km, ice-filled summit caldera whose depth may exceed 1 km (Benson and Motyka, 1979). The caldera is apparently of non-explosive origin (Richter and others, 1984) formed in response to the withdrawal of magma from high-level reservoirs beneath the summit area. Three small (<1 km in diameter) post-caldera craters, all geothermally active, occur along the west and north margin of the caldera. Mt. Zanetti (3965 m) a large (450 m high) steep-sided, relatively undissected cinder-spatter cone occurs high on the northwest flank of the shield and may be the source of some lava flows. Lavas on the southwest flank have flowed as much as 58 km from their source despite being phenocryst-rich andesite, a mobility attributed to a very high eruption rate (Nye, 1983)."