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Lahar Hazards at Crater Lake

Lahars originating from renewed volcanic activity at Mount Mazama would most likely be a result of the mixing of a pyroclastic material with a large release of water. This would occur if lake water were rapidly ejected from the caldera during a volcanic eruption or if hot volcanic products mixed with and melted a large amount of snow. Geologic evidence of lahars originating on Mount Mazama is sparse, though it is likely that older lahar deposits were eroded and/or buried by pyroclastic flows that swept the valleys during the caldera-forming eruption 7,700 years ago.