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

Science on the Leading Science on the Leading Edge: Plate tectonics on Edge: Plate tectonics on

Canada’s West CoastCanada’s West Coast

Bamfield Marine Sciences Centre, Public Education ProgramTeachers Workshop, October 24, 2008

Pacific Geosciences Centre

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)NRCANGeological Survey of Canada, Pacific Geosciences Centre, (Jane Wynne, Mike Schmidt in particular)University of VictoriaNEPTUNE CanadaUNAVCOAll 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 to www.bms.bc.ca

ObjectivesObjectives

1.1. Link plate tectonics to British Columbia’s Link plate tectonics to British Columbia’s current geologic situationcurrent geologic situation

2.2. Visualize the movement of local tectonic Visualize the movement of local tectonic platesplates

3.3. Make connections between plate Make connections between plate movement, sub-sea ridges, divergence, movement, sub-sea ridges, divergence, subduction, earthquakes, tsunamis and subduction, earthquakes, tsunamis and volcanoesvolcanoes

4.4. Use real-time data to plot the movement Use real-time data to plot the movement of GPS stations at Victoria and Seattleof GPS stations at Victoria and Seattle

Tectonic PlatesTectonic Plates

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

‘‘Creation and destruction’ of Creation and destruction’ of plates.plates.

Divergence: two Divergence: two plates moving plates moving away from each away from each otherother

Subduction: a Subduction: a dense, heavy dense, heavy oceanic plate oceanic plate “slides” under a “slides” under a lighter continental lighter continental plateplate

Seafloor SpreadingSeafloor Spreading

Magma rises to the Magma rises to the seafloor through a seafloor through a series of fracturesseries of fractures

Cools, then sticks Cools, then sticks to walls forming to walls forming vertical sheetsvertical sheets

Ocean crust Ocean crust spreads in both spreads in both directions away directions away from the ridgefrom the ridge

University of Washington& NOAA

Juan de Fuca Ridge: Deep Sea VentJuan de Fuca Ridge: Deep Sea Vent http://ess.nrcan.gc.ca/esic/gallery/images/1994-731.p.jpg http://ess.nrcan.gc.ca/esic/gallery/images/1994-731.p.jpg

Juan de Fuca ridge, underwater Juan de Fuca ridge, underwater volcanoes.volcanoes.

VolcanoesVolcanoes

Image: Google Earth

Volcanoes lie Volcanoes lie above the deep above the deep subducting crust subducting crust which is hot which is hot enough to melt the enough to melt the mantle abovemantle above

Hot, buoyant Hot, buoyant magma rises up to magma rises up to erupt at the erupt at the surfacesurface

Juan de Fuca PlateJuan de Fuca Platehttp://cgc.nrcan.gc.ca/geodyn/imageshttp://cgc.nrcan.gc.ca/geodyn/images

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

EarthquakesEarthquakes Southwestern British Columbia Earthquakes in Southwestern British Columbia Earthquakes in

the last 30 days (from nrcan.gc.ca)the last 30 days (from nrcan.gc.ca)

Not all months are created Not all months are created equally.equally.

Earthquakes Aug 14 - Sept 13Earthquakes Aug 14 - Sept 13

There’s a whole lot of shaking There’s a whole lot of shaking going on.going on.

http://earthquakescanada.nrcan.gc.cahttp://earthquakescanada.nrcan.gc.ca

Five years worth of shaking.

Vancouver Island Vancouver Island EarthquakesEarthquakes

Epicenters are located along plate margins Epicenters are located along plate margins and above subduction zones (faults)and above subduction zones (faults)

Earthquakes are mostly magnitude 2-4 on Earthquakes are mostly magnitude 2-4 on the Richter scale the Richter scale • Eg. magnitude 3 would move the ground about Eg. magnitude 3 would move the ground about

one millimetreone millimetre The Cascadia Subduction fault is locked at The Cascadia Subduction fault is locked at

a depth of 20km – brittle rock and rock a depth of 20km – brittle rock and rock above are being flexed above are being flexed

Eventually a slip will occur causing another Eventually a slip will occur causing another large earthquakelarge earthquake

Mt. St. Helens, USGS

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

The great 1700 EarthquakeThe great 1700 Earthquake

This mathematical model of the January 26, 1700 megathrust earthquake shows the wave as it reaches Hawaii. . http://geoscape.nrcan.gc.ca/victoria/bigone_e.php

Is there evidence the plates are Is there evidence the plates are actually moving?actually moving?

Data collected by a network of Data collected by a network of GPS (Global Positioning System) GPS (Global Positioning System) receivers track the exact receivers track the exact position of nodesposition of nodes

• Compare moving GPS nodes to Compare moving GPS nodes to stationary nodes further inlandstationary nodes further inland

• Measure how far and in which Measure how far and in which direction the crust is deformingdirection the crust is deforming

• We will have a look at the data and We will have a look at the data and graph the location vectorsgraph the location vectors

• 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 Western Canada Deformation Array (WCDA)(WCDA)

Latitude Latitude (north/south)(north/south)

Longitude Longitude (east/west)(east/west)

ElevationElevation

GPS technology used to measure GPS technology used to measure continental crust movement.continental crust movement.

Movement of Victoria GPS Station (East-West) Movement of Victoria GPS Station (East-West)

and Correlation with Tremor Activityand Correlation with Tremor Activity

What the data looks like.What the data looks like. Download as a .csv file, save as an Excel file, use Excel to Download as a .csv file, save as an Excel file, use Excel to

graph and calculate regression line and slopegraph and calculate regression line and slope Use the slope of the line (mm/day) to calculate average Use the slope of the line (mm/day) to calculate average

yearly movementyearly movement

Remember, when looking at graphs:Remember, when looking at graphs:

Check the axes and Check the axes and the unitsthe units

Look for trendsLook for trends The slope of line is The slope of line is

simply rise/run (or simply rise/run (or change in y over change in y over change in x)change in x)

Let’s look at some near real-time GPS Let’s look at some near real-time GPS data from Victoria & Seattledata from Victoria & Seattle

We are going to plot vectors for We are going to plot vectors for Victoria and Seattle GPS nodesVictoria and Seattle GPS nodes• You have a data table with four boxesYou have a data table with four boxes• Victoria eastward is already calculatedVictoria eastward is already calculated• Use the slope (mm/day) X 365.25 days/year to calculate Use the slope (mm/day) X 365.25 days/year to calculate

average annual velocityaverage annual velocity

Calculate velocity by multiplying slope by Number of days in year. Slope (in mm/day) x (number of days/year) = average yearly velocity GPS Station Victoria (Albert Head), BC

East - west average velocity (mm/yr) Is it moving to the east or to the west?

0.0148 mm/day x 365.25 days/year =

5.406 mm per year

_East______________________

Example:

Movement East (mm) in Victoria (Albert Head) from 2004 - 2008

y = 0.0148x - 553.7

-20

-15

-10

-5

0

5

10

15

20

8/29/03 3/16/04 10/2/04 4/20/05 11/6/05 5/25/06 12/11/06 6/29/07 1/15/08 8/2/08 2/18/09

Time (days)

Eastward movement (mm) Y= 0.0148x - 553.7

Slope = 0.0148 mm/day

Nothward movement at Victoria

y = 0.0114x - 425.35

-15

-10

-5

0

5

10

15

8/29/03 3/16/04 10/2/04 4/20/05 11/6/05 5/25/06 12/11/06 6/29/07 1/15/08 8/2/08 2/18/09

Time in days

Movement north (mm)

Y = 0.0114 x - 425.35

Slope = 0.0114____ mm/day

Seattle moving East (mm)

y = 0.0108x - 404.19

-15

-10

-5

0

5

10

15

8/29/03 3/16/04 10/2/04 4/20/05 11/6/05 5/25/06 12/11/06 6/29/07 1/15/08 8/2/08 2/18/09

Time (days)

East movement (mm)

Y = 0.0108x - 404.19

Slope = _____ mm/day

y = 0.0092x - 342.93

-15

-10

-5

0

5

10

15

8/29/03 3/16/04 10/2/04 4/20/05 11/6/05 5/25/06 12/11/06 6/29/07 1/15/08 8/2/08 2/18/09

Y = 0.0092x - 342.93

This is the last graph for this exercise. What is missing?

What is the slope of the line?

Seattle north

How to plot a vector.How to plot a vector.

North

South

West East0

Start at zeroStart at zero Mark how far east and and Mark how far east and and

how far northhow far north Make a pointMake a point Draw a line from 0 to the Draw a line from 0 to the

pointpoint Put an arrowhead on the Put an arrowhead on the

pointpoint

Point

Congratulations! You made a vector Congratulations! You made a vector that shows magnitude and direction that shows magnitude and direction

of movement.of movement.

Now, draw the Victoria & Seattle vectorsNow, draw the Victoria & Seattle vectors

DiscussionDiscussion Compare the vectorsCompare the vectors

Why do Ucluelet and Neah Why do Ucluelet and Neah Bay vectors have so much Bay vectors have so much more velocity?more velocity?

Predict the vertical Predict the vertical movement at Ucluelet and movement at Ucluelet and Neah Bay vs more Eastern Neah Bay vs more Eastern nodes?nodes?

What are some sources of What are some sources of error?error?

http://cgc.rncan.gc.ca/geodyn/cascadia_e.php

What’s next? Extending the What’s next? Extending the network to the seafloor.network to the seafloor.

NEPTUNE Canada NEPTUNE Canada will provide real-will provide real-time data on time data on seismic activity to seismic activity to shore via a shore via a powered fiber-optic powered fiber-optic cable.cable.

Cabled-laying system on ROPOSROPOS Canada copyright