Postglacial lahars and potential hazards in the White Salmon River system on the southwest flank of Mount Adams, Washington

Mount Adams, a stratovolcano in southwestern Washington State, formed during Pleistocene time and reached roughly its present size before the end of the Fraser glaciation, which occurred between 25,000 and 12,000 years ago. Since the last glaciation, Mount Adams has erupted at least nine times, producing eight peripheral lava flows and a cinder cone at the summit but no pyroclastic flows. No stratigraphic evidence was found for the occurrence of lahars concurrently with eruptions; in fact, at least one lahar and one debris avalanche occurred during apparently dormant intervals.