Learning and teaching resources on Cascadia volcanoes and their associated hazards are provided in this section. We explain the origins of and chemistries of magma and how these are related to plate tectonics in general and Cascadia regional plate tectonics in particular. The types of volcanoes and the explosiveness of their eruptions are addressed by examining the “three Vs of volcanology”, viscosity, volatiles, and volume. Major volcanic provinces and the importance of volcanic rocks in the geologic history of the Pacific Northwest are outlined. Cascadia volcanic hazards include ash flows, ash fall, and volcanic mud and debris flows. We provide a short introduction to methods of monitoring volcanic activity and warning signs of impending eruption.
We recommend that you start by viewing the Cascadia Volcanoes and Volcanic Hazards PowerPoint Presentation. This presentation provides the basic concepts and observations as well as links the teaching resources appropriate for a middle school audience.
A PDF Guide to Cascadia Volcanoes and Volcanic Hazards is also available. This guide is an outline of the Cascadia Volcanoes and Volcanic Hazards topic that contains links to and a table of contents of TOTLE teaching resources on this topic.
This animation shows the three-dimensional views of the Cascadia subduction zone. The Juan de Fuca Plate is created at the Juan de Fuca Ridge, then subducts beneath the Pacific Northwest portion of the North American Plate. The location of earthquakes, generation of magma, upward migration of magma, and eruption of Cascade volcanoes are illustrated.
Gases such as CO2 and SO2 are contained within magma that rises beneath volcanoes. Gas emissions often increase and change composition prior to volcanic eruptions. monitoring of gas emissions has become an important component of volcano monitoring programs. This animation explains the principles of volcanic gas monitoring using ultraviolet spectrometry. The animation was developed by the Mt St Helens Institute, US Geological Survey Johnston Ridge Observatory, IRIS, and EarthScope.
Earthquakes of small magnitude and shallow depth often occur beneath volcanoes that are approaching eruption. These earthquakes are caused by heating of rocks beneath the volcano as magma works its way up into shallow chambers beneath the volcano and by pressure changes within the rising magma. This animation explains the principles of seismic monitoring of volcanoes. The animation was developed by the Mt St Helens Institute, US Geological Survey Johnston Ridge Observatory, IRIS, and EarthScope.
This animation was developed by the Educational Multimedia Visualization Center of the Department of Earth Science, University of California at Santa Barbara, under the direction of Professor Tanya Atwater. The animation shows how subduction of an oceanic plate beneath a continental plate can produce an accretionary wedge of oceanic sediment and “lights the lava lamp” by generating magma in the asthenospheric mantle above the subducting plate.
The shape of the ground surface on or around a volcano sometimes precedes volcanic eruptions. Monitoring the shape of volcanoes has become an important component of volcano monitoring programs. This animation explains the principles of GPS and tiltmeter monitoring of volcanoes. The animation was developed by the Mt St Helens Institute, US Geological Survey Johnston Ridge Observatory, IRIS, and EarthScope.