This student worksheet is to be used as part of the Cascadia GPS Gumdrop Lesson Plan. The worksheet is an MS Word document and can be edited by the teacher for use in their classes.
Roger Groom, Mt Tabor Middle School, developed this activity with assistance from Bob Butler, University of Portland, and Shelley Olds and Becca Walker, UNAVCO. This activity allows students to analyze high-precision differential GPS observations of deformation of the North American Plate near its boundary with the oceanic Juan de Fuca Plate. Students analyze the rates of motion of three GPS receiving stations at different distances from the Cascadia subduction zone boundary. Through this activity, students appreciate how GPS monitors the gradual buildup of elastic energy as the continental margin within the Pacific Northwest is compressed by convergence between the North American and Juan de Fuca plates. This slowly accumulating elastic energy will be released in the next Cascadia megathrust earthquake!
Poster illustrates the violence of ground shaking expected for three kinds of earthquakes: (1) Cascadia subduction zone great earthquake; (2) “deep” earthquake within subducting Juan de Fuca Plate beneath Pacific Northwest (e.g. Nisqually 2001); and (3) local magnitude 7 earthquake on the Seattle Fault.
Poster illustrates the violence of ground shaking expected for three kinds of earthquakes: (1) Cascadia subduction zone great earthquake; (2) “deep” earthquake within subducting Juan de Fuca Plate beneath Pacific Northwest (e.g. Nisqually 2001); and (3) local magnitude 7 earthquake on Portland Hills Fault.
Word format file on liquefaction containing a student worksheet.
Relative earthquake hazard maps compare the expected violence of earthquake ground shaking and likely damage over a map area produced by a generic earthquake outside of the mapped region. Relative earthquake hazard maps are usually a combination of several different earthquake risks added together. For example, the Oregon Department of Geology and Mineral Industries (DOGAMI) constructed relative earthquake hazard maps for regions in Oregon by combining slope instability (landslide), amplification of ground shaking by weak near-surface geology, and liquefaction potential into one map. Areas of particularly high earthquake risk are mapped as “red zones” often because of high liquefaction potential near waterways (rivers and lakes) or because of large thickness of weak near-surface geologic layers such as unconsolidated sediments. This classroom activity combines three related activities into one: a slope instability demonstration; a ground amplification demonstration; and a liquefaction experiment.