Belknap Crater
There are about 6,500 people living within of Belknap Crater, with a population of about 362,000 within . However, most eruption hazards from basaltic volcanoes are generally restricted to within of the vent, with some exceptions. According to the Volcano Hazards Program of the United States Geological Survey's Cascades Volcano Observatory, the threat potential from Belknap is "Low/Very Low". It does not seem likely that Belknap Crater will erupt again, though eruptions with similar characteristics to its past eruptions might occur in the surrounding area, disrupting transportation on major highways in the vicinity including U.S. Route 20, Oregon Route 22, and Oregon Route 242. The eruption of tephra could pose a threat to surrounding communities, particularly within central Oregon to the east. High-volume lahars (mudflows or debris flows composed of a mix of pyroclastic material, rocky debris, and water) would travel far to the west. Moreover, low-volume lahars from eruptions would likely enter the McKenzie River valley, which is broad and fairly gently sloped, where they might move downstream through flood plains or small channels. Near Belknap Springs and McKenzie Bridge, deposits from the eruption could also block off water upstream, leading to downstream lahars and floods.