1. Science on the Leading Edge: Plate tectonics on Canada’s West Coast
The Bamfield Marine Sciences Centre is located on the outer edge of Vancouver Island’s west coast. The Public Education Program works with teachers and students to promote science learning with a focus on the ocean and connections to the ocean.
Bamfield Marine Sciences Centre, Public Education Program
Teachers Workshop, October 24, 2008
Pacific Geosciences Centre

2. Thanks to www.bms.bc.ca 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 go out to all the groups and individuals who made the SOLE learning material available for teachers and students.

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

4. Where in the world is the Juan de Fuca plate?
Tectonic Plates
The Earths crust is made up of tectonic plates that slowly move on currents of molten rock or magma. Continental plates are less dense and tend to float over dense metal laden oceanic plates.
Where in the world is the Juan de Fuca plate?
Hint: it is very small.

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

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

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

8. Volcanoes
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
Image: Google Earth

9. Juan de Fuca Plate http://cgc.nrcan.gc.ca/geodyn/images

10. Block diagram of Southwest B.C., showing features.
Sub-sea ridge, divergence, Pacific Plate (dense), Juan de Fuca Plate (dense), spreading at ridge, size of Earth not increasing, North American Plate (more buoyant), movement, subduction zone, brittle part sticky, melting part, volcanoes, (use lasagna analogy)
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

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

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

13. There’s a whole lot of shaking going on.
Five years worth of shaking.

14. Vancouver Island Earthquakes
Epicenters are located along plate margins and above subduction zones (faults)
Earthquakes are mostly magnitude 2-4 on the Richter scale
Eg. 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
Eventually a slip will occur causing another large earthquake

15. wood-block print, the Great Wave off the Coast of Kanagawa,
Tsunami, Adapted from a
wood-block print, the
Great Wave off the
Coast of Kanagawa,
by Hokusai.
The December 2004, Sumatra, Indonesian Islands earthquake rupture area is similar in size to the Cascadia subduction zone. The last megathrust earthquake here was in January The tsunami from that quake was devastating to coastal communities here and in Japan.
Mt. St. Helens, USGS

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

17. 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
Compare moving GPS nodes to stationary nodes further inland
Measure how far and in which direction the crust is deforming
We will have a look at the data and graph the location vectors
The Geological Survey of Canada runs the permanent GPS tracker network that investigates crustal deformation in British Columbia. It is called the Western Canada Deformation Array and it produces measurements for Canadian and International scientists.

18. Western Canada Deformation Array (WCDA)
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

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

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

21. 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
Use the slope of the line (mm/day) to calculate average yearly movement
The UNAVCO web-site (Outreach & Education) has current data that can be down-loaded so that the class is working with near real-time data

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

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

24. Y= x
Slope = mm/day

25. Y = x
Slope = ____ mm/day

26. Y = x
Slope = _____ mm/day

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

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

29. Discussion Compare the vectors
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?
What are some sources of error?

30. What’s 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.
Cabled-laying system on ROPOS
ROPOS Canada copyright