USING EarthScope GPS DATA IN MIDDLE SCHOOL LESSON PLANS ON CONTINENTAL MARGIN DEFORMATION IN THE PACIFIC NORTHWEST

We developed lesson plans that help Pacific Northwest middle school Earth science students understand how plate tectonic forces are moving the ground beneath their feet. In a basic activity, students build a gumdrop GPS monument, analyze GPS time series plots from three PBO stations on a transect from coastal to eastern Washington, and discover that the Pacific Northwest is being compressed between the Juan de Fuca Plate and the North American interior. The required instructional time is justified because the lesson applies graphical analysis, a fundamental skill of science and mathematics. Extensions to the basic introduction to GPS lesson are: (1) Analysis of data from an array of GPS stations across Oregon and Washington that shows the ‘locked and loading’ nature of the continental margin as it stores elastic energy to be released in the next great Cascadia subduction zone earthquake. (2) Analysis of motions between Pacific Northwest crustal blocks caused by Basin and Range extension and northwest motion of the Sierra Nevada block. We use a physical model (developed by Ray Wells, US Geological Survey) with sliding panels representing crustal blocks to help students grasp the geometry of crustal block motions. An important outcome is that block motions explain why crustal earthquakes pose a higher seismic risk to the Puget Sound region than to other areas of the Pacific Northwest. (3) Analysis of motions of PBO stations in the eastern Coast Ranges and urban corridor can allow students to ‘discover’ Episodic Tremor and Slip (ETS) and appreciate how new technologies can reveal previously undiscovered plate tectonic processes. In this lesson, students explore how temperature affects the motion of the subducting Juan de Fuca Plate and how ETS may increase stress on the locked portion of the Cascadia subduction zone with important implications for megathrust earthquake and tsunami hazards. We use a two-block ‘earthquake machine’ model to help students understand the connections between motions of the Juan de Fuca Plate in the ETS zone and stress on the shallower locked portion of the subduction zone. The graduated structure of these lesson plans allows teachers to infuse their classroom teaching with cutting edge EarthScope science while adhering to time constraints of the middle school Earth science curriculum.