Mount Adams has not erupted during the past 1,000 years, and even though it has been less active than neighboring Mounts St. Helens and Rainier, it will assuredly erupt again. The geological record of activity suggests that the most probable future eruptions would be small outbursts of tephra and lava flows from vents on the summit and upper flanks of the volcano rather than from the surrounding volcanic field. If lava flows occur on steep upper flanks, the leading edge of the flow could crumble and cause pyroclastic flows, which could mix with water to form lahars. One of the largest threats is from a large debris avalanche originating from the upper part of the main cone, which could create catastrophic lahars along downslope drainages. Such large landslides and lahars need not be related to eruptive activity, although they commonly are.