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Science on the Leading Edge: Plate tectonics on Canadas West Coast Bamfield Marine Sciences Centre, Public Education Program Teachers Workshop, October 24, 2008 Pacific Geosciences Centre

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Kim Juniper (for the idea) Western Canadian Universities Marine Sciences Society Bamfield Marine Sciences Centre Natural Sciences and Engineering Research Council (NSERC) PromoScience (Funding) EdGeo (funding for teachers workshop, we hope) NRCAN Geological Survey of Canada, Pacific Geosciences Centre, (Jane Wynne, Mike Schmidt in particular) University of Victoria NEPTUNE Canada UNAVCO All the pilot teachers and students from Calgary Science School, Robert Bateman Sec., Summerland Sec., St. Michaels Univ. School, Mark Islfeld Sec., Crestwood School And many others… Thanks towww.bms.bc.ca

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Objectives 1. Link plate tectonics to British Columbias current geologic situation 2. Visualize the movement of local tectonic plates 3. Make connections between plate movement, sub-sea ridges, divergence, subduction, earthquakes, tsunamis and volcanoes 4. Use real-time data to plot the movement of GPS stations at Victoria and Seattle

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Tectonic Plates Where in the world is the Juan de Fuca plate? Hint: it is very small.

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Creation and destruction of plates. Divergence: two plates moving away from each other Divergence: two plates moving away from each other Subduction: a dense, heavy oceanic plate slides under a lighter continental plate Subduction: a dense, heavy oceanic plate slides under a lighter continental plate

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Seafloor Spreading Magma rises to the seafloor through a series of fractures Magma rises to the seafloor through a series of fractures Cools, then sticks to walls forming vertical sheets Cools, then sticks to walls forming vertical sheets Ocean crust spreads in both directions away from the ridge Ocean crust spreads in both directions away from the ridge University of Washington & NOAA

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Juan de Fuca Ridge: Deep Sea Vent Juan de Fuca ridge, underwater volcanoes.

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Volcanoes Image: Google Earth Volcanoes lie above the deep subducting crust which is hot enough to melt the mantle above Volcanoes lie above the deep subducting crust which is hot enough to melt the mantle above Hot, buoyant magma rises up to erupt at the surface Hot, buoyant magma rises up to erupt at the surface

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Juan de Fuca Plate

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Block diagram of Southwest B.C., showing features. Turner, R. J. W., Clague, J. J., Groulx, B. J.,1998: Geoscape Vancouver, living with our geological landscape; Geological Survey of Canada, Open File 3309

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Earthquakes Southwestern British Columbia Earthquakes in the last 30 days (from nrcan.gc.ca) Southwestern British Columbia Earthquakes in the last 30 days (from nrcan.gc.ca)

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Not all months are created equally. Earthquakes Aug 14 - Sept 13

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Theres a whole lot of shaking going on. Five years worth of shaking.

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Vancouver Island Earthquakes Epicenters are located along plate margins and above subduction zones (faults) Epicenters are located along plate margins and above subduction zones (faults) Earthquakes are mostly magnitude 2-4 on the Richter scale Earthquakes are mostly magnitude 2-4 on the Richter scale Eg. magnitude 3 would move the ground about one millimetreEg. magnitude 3 would move the ground about one millimetre The Cascadia Subduction fault is locked at a depth of 20km – brittle rock and rock above are being flexed The Cascadia Subduction fault is locked at a depth of 20km – brittle rock and rock above are being flexed Eventually a slip will occur causing another large earthquake Eventually a slip will occur causing another large earthquake

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Mt. St. Helens, USGS Tsunami, Adapted from a wood-block print, the Great Wave off the Coast of Kanagawa, by Hokusai.

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The great 1700 Earthquake This mathematical model of the January 26, 1700 megathrust earthquake shows the wave as it reaches Hawaii..

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Is there evidence the plates are actually moving? Data collected by a network of GPS (Global Positioning System) receivers track the exact position of nodes Data collected by a network of GPS (Global Positioning System) receivers track the exact position of nodes Compare moving GPS nodes to stationary nodes further inlandCompare moving GPS nodes to stationary nodes further inland Measure how far and in which direction the crust is deformingMeasure how far and in which direction the crust is deforming We will have a look at the data and graph the location vectorsWe will have a look at the data and graph the location vectors

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Permanent GPS Tracker Network Geological Survey of Canada Measures plate deformation in the Cascadia Subducation Zone Seismic hazard in densely populated region of British Columbia Western Canada Deformation Array (WCDA)

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Latitude (north/south) Latitude (north/south) Longitude (east/west) Longitude (east/west) Elevation Elevation GPS technology used to measure continental crust movement.

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Movement of Victoria GPS Station (East-West) and Correlation with Tremor Activity

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What the data looks like. Download as a.csv file, save as an Excel file, use Excel to graph and calculate regression line and slope Download as a.csv file, save as an Excel file, use Excel to graph and calculate regression line and slope Use the slope of the line (mm/day) to calculate average yearly movement Use the slope of the line (mm/day) to calculate average yearly movement

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Remember, when looking at graphs: Check the axes and the units Check the axes and the units Look for trends Look for trends The slope of line is simply rise/run (or change in y over change in x) The slope of line is simply rise/run (or change in y over change in x) Lets look at some near real-time GPS data from Victoria & Seattle

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We are going to plot vectors for Victoria and Seattle GPS nodes You have a data table with four boxes You have a data table with four boxes Victoria eastward is already calculated Victoria eastward is already calculated Use the slope (mm/day) X days/year to calculate average annual velocity Use the slope (mm/day) X days/year to calculate average annual velocity Example:

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Y= x Slope = mm/day

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Y = x Slope = ____ mm/day

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Y = x Slope = _____ mm/day

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Y = x This is the last graph for this exercise. What is missing? What is the slope of the line? Seattle north

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How to plot a vector. North South WestEast 0 Start at zero Start at zero Mark how far east and and how far north Mark how far east and and how far north Make a point Make a point Draw a line from 0 to the point Draw a line from 0 to the point Put an arrowhead on the point Put an arrowhead on the point Point Congratulations! You made a vector that shows magnitude and direction of movement. Now, draw the Victoria & Seattle vectors Now, draw the Victoria & Seattle vectors

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Discussion Compare the vectors Compare the vectors Why do Ucluelet and Neah Bay vectors have so much more velocity? Why do Ucluelet and Neah Bay vectors have so much more velocity? Predict the vertical movement at Ucluelet and Neah Bay vs more Eastern nodes? Predict the vertical movement at Ucluelet and Neah Bay vs more Eastern nodes? What are some sources of error? What are some sources of error?

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Whats next? Extending the network to the seafloor. NEPTUNE Canada will provide real- time data on seismic activity to shore via a powered fiber-optic cable. NEPTUNE Canada will provide real- time data on seismic activity to shore via a powered fiber-optic cable. Cabled-laying system on ROPOS ROPOS Canada copyright

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