USING THE 1700 CASCADIA EARTHQUAKE AND TSUNAMI TO EXCITE SECONDARY-SCHOOL STUDENTS ABOUT EARTH SCIENCE

The scientific detective story of the giant 1700 Cascadia earthquake and the associated tsunami provides a launch point for middle school and high school studies of geologic hazards, active continental margin geology, and EarthScope science. Drawing on “The Orphan Tsunami of 1700” (http://pubs.usgs.gov/pp/pp1707), we have developed classroom activities that invite students to approach Cascadia's earthquake tsunami geology as a “Crime Scene Investigation”. Students can examine: (1) a three-layer cake (forest soil overlain by tsunami sand and then by tidal-flat mud) that records both the sudden lowering of coastal land during an earthquake and the ensuing tsunami; (2) tree rings from earthquake victims, cross-dated to and from “witness” trees on high ground, that assign the most recent of Cascadia's great earthquakes to the months between August 1699 and May 1700; (3) columns of Japanese writing about a tsunami of remote origin that pinpoint this Cascadia earthquake to the evening of January 26, 1700; and (4) Plate Boundary Observatory data from continuous GPS stations showing the coast moving inland, the Willamette Valley and Puget Lowland also moving inland but more slowly, and hardly any motion at all east of the Cascades—observations that lead students to the realization that the Juan de Fuca – North America plate boundary is “locked and loading” as it stores elastic energy that will be released in the next great Cascadia earthquake. Inquiry-based learning about great Cascadia earthquakes and tsunamis aligns well with National Science Education Standards; provides a case study of scientific discovery, an important benchmark of science literacy; and emphasizes science, technology, and societal connections through consideration of geologic hazards.