United States Geological Survey Reports

From introduction: This report describes the character, origin, age, and extent of deposits of pyroclastic flows and lahars that were formed at Mount St. Helens before 1980, and their stratigraphic relations to other rocks and deposits of volcanic and glacial origin

United States Geological Survey Reports

From introduction: Much of the ground surface around Mount Rainier volcano is directly underlain by loose geologic deposits that veneer the hard rock formations. Examples of these deposits are sand and gravel bars along the rivers, ridges of loose rock debris beside the glaciers, and sloping aprons of rock fragments beneath almost every cliff. Even though they are generally thin and inconspicuous when compared with the rock formations, these surficial deposits are clues to geologic events that. have profoundly influenced the shape of the park's landscape. Thus, from the character and extent of glacial deposits one can judge the age and size of former glaciers that carved the cirques and deep canyons of the park; from the mudflows which streamed down nearly every valley one can infer the age and size of huge landslides of the past that helped determine Mount Rainier's present shape; and from the pumice deposits some of the volcano's recent eruptive activity can be reconstructed

United States Geological Survey Professional Paper 1022-C

Abstract: Eruptions and other geologic events at Mount Baker during the last 10,000 years have repeatedly affected adjacent areas, especially the valleys that head on the south and east sides of the volcano. Small volumes of tephra were erupted at least four times during the past 10,000 years. Future eruptions like these could cause as much as 35 centimeters of tephra to be deposited at sites 17 kilometers from the volcano, 15 centimeters of tephra to be deposited 29 kilometers from the volcano, and 5 centimeters, 44 kilometers from the volcano. Lava flows were erupted at least twice during the last 10,000 years and moved down two valleys. Future lava flows will not directly endanger people because lava typically moves so slowly that escape is possible. Hot pyroclastic flows evidently occurred during only one period and were confined to the Boulder Creek valley. Such flows can move at speeds of as much as 150 kilometers per hour and can bury valley floors under tens of meters of hot rock debris for at least 15 kilometers from the volcano. Large mudflows, most of which contain hydrothermally altered rock debris, originated at Mount Baker at least eight times during the last 10,000 years. The largest mudflow reached 29 kilometers or more down the valley of the Middle Fork Nooksack River, west of the volcano, about 6,000 years ago. Extensive masses of hydrothermally altered rock that are potentially unstable exist today near the summit of the volcano, especially in the Sherman Crater-Sherman Peak area. Avalanches of this material could be triggered by stream explosions, earthquakes, or eruptions, or may occur because of slow-acting forces or processes that gradually decrease stability. Large avalanches could move downslope at high speed and could grade downvalley into mudflows. Floods caused by rapid melting of snow and ice by lava or by hot rock debris could affect valley floors many tens of kilometers from the volcano and could have especially severe effects if they were to occur at a time of flooding resulting from rapid snowmelt or heavy rains

Volcanic hazards in the Hawaiian Islands

Chapter 22 of Volcanism in HawaiiVolcanism in Hawaii: Chapter 22. Volcanic eruptions have built the Hawaiian Islands, and similar eruption. in the future will affect many area in them, especially on Kilauea and Mauna Loa Volcanoes on the Island of Hawaii. Some of those eruptions will endanger people and property. Hazards that result directly, from eruptions include lava flows, tephra fells, volcanic gases, and pyroclastic surge. Lees direct hazards associated with eruption. Include ground fracture and subsidence, earthquakes, and tsunami. The Islands of Hawaii and Maui have been subdivided on maps, for some kind of hazards, into various zones of differing magnitude of hazard. These hazard-zone maps can be used for making land-use decisions before eruptions occur and for responding to actual or threatened eruptions, Hazard-zone map for earthquake and tsunamis are not included in this report; however, earthquakes of both volcanic and nonvolcanic origin can affect extensive areas in the islands, and tsunami can be highly damaging in narrow coastal zones. Because most volcanic events cannot be effectively controlled, volcanic hazards are best avoided by land-use planning before eruptions occur and by evacuation when they do occur. Mitigation measures to reduce effects from lava flow can be effective, at least temporarily, but such measures are generally more effective for some other hazard such as tephra fall and volcanic gases