Earthquakes in Canada

Canada experiences thousands of earthquakes each year, even if most are not felt on the surface.  Of the 3,900 seismic events recorded in Canada in the last year, only 700 were a 3 or above on the Richter scale.  Of those, only 13 at registered a 5 or higher.  The majority of these events occur on the pacific coast, particularly in British Columbia.  A large earthquake in a densely populated area along the western Canadian coast would be the most destructive and most likely natural disaster to occur in Canada.      

In areas of Canada that are impacted by earthquakes, there strict building codes designed to greatly reduce the risk of structure collapse. However, studies over the last several decades show that you are more likely to be injured by falling or flying household items than to die in a collapsed building.  Because of this, Canada has been promoting “Drop, Cover, and Hold On” in the event of an earthquake.  This technique can prevent injury in the event of an earthquake that causes falling debris.  In addition, it has also been shown that sturdy tables and desks often hold their ground when a building collapses, often supporting the collapsing floor from above.        

The National Building Codes are used to design and constructing buildings to be as resistant to earthquake damage as possible.  While this code is used to take every precaution necessary, there large earthquakes can still cause serious damage to any building.  There are very different sets of standards for western and eastern Canada.  The measures on the west coast are much more rigorous, as the majority of Canada’s seismic activity occurs along the Juan de Fuca, the North American, and the Pacific plates.  

http://www.earthquakescanada.nrcan.gc.ca/info-gen/prepare-preparer/index-eng.php

http://www.embc.gov.bc.ca/em/hazard_preparedness/Earthquake_Information.html

http://www.getprepared.gc.ca/cnt/hzd/rthqks-en.aspx

http://www.nrc-cnrc.gc.ca/eng/dimensions/issue8/earthquakes.html

The Plates of Canada

   Along the western coast of Canada, we can see examples of all three types of tectonic plate boundaries.  There are areas that are convergent, divergent, and transform.  There are frequent earthquakes throughout Canada, with the western coast of British Columbia being the most active area.  The three major plates are the Juan de Fuca, the North American, and the Pacific.  Each of these plates interacts with the other in a very unique way.

   The area where the Juan de Fuca plate meets the North American plate is convergent.  The long line of volcanoes down the pacific coast was created by a subduction zone.  The Juan de Fuca plate is slowly shifting under the North American plate, which created the volcanoes Mount Meager and Mount Garibaldi.  This subduction is also responsible for the Cascade Mountains in the United States.  While the most recent volcanic eruption was at Mount Meager over 2350 years ago, there are hundreds of small earthquakes along this line each year.  Currently, the Juan de Fuca plate is locked with the North American plate, causing extreme pressure that could eventually lead to a magnitude 8 or higher earthquake along the British Columbia coast. 

   About 170 miles off the coast of Vancouver, the Juan de Fuca plate meets the Pacific plate.  This meeting is divergent, and is slowly pushing the two plates away from each other.  As this happens, magma from the earth’s mantle fills in the gaps of these breaks in the ocean floor.  Since the two plates are moving away from one another, they are adding to the ocean floor.  There are many small earthquakes along this fault as a result of the plate activity.

   The area where the North American Plate and the Pacific plate interact along the Canadian coast is called the Queen Charlotte Fault.  At this point the North American Plate is moving southeast, while the Pacific plate is moving northwest, which creates a Transform fault line.  The Queen Charlotte fault is very similar to the San Andreas Fault here along the California coastline.  Like the San Andreas Fault, the Queen Charlotte fault is responsible for some of the largest seismic activity ever recorded in Canada.

   The Eastern portion of Canada is located in the center for the North American Plate, and does not fall on any fault lines.  Although it is not on any fault line, each year there are up to 450 earthquakes throughout eastern Canada.  Since these earthquakes do not occur on a major fault line, many are not felt on the surface and as few as 3 per year will be above a magnitude 5.  While the origin of these quakes is bit of a mystery, they have been attributed to weaknesses in the earth’s crust.  The North American plate extends well past the eastern coast of Canada, and results in very little seismic activity.   

This figure represents the seismic activity in Canada in the last 30 days alone (January 20th- February 20th, 2015).  There are 545 recorded examples of seismic activity, however most are a 2 or lower in magnitude, with only 6 reaching a 4 on the Richter scale.

http://www.earthquakescanada.nrcan.gc.ca/zones/westcan-eng.php

http://www.earthquakescanada.nrcan.gc.ca/zones/eastcan-eng.php

http://www.earthquakescanada.nrcan.gc.ca/index-eng.php

http://www.earthquakescanada.nrcan.gc.ca/pprs-pprp/pubs/GF-GI/GEOFACT_plate-tectonics_e.pdf

Canadian Mining and Rock Composition

Canada has a long history of mining minerals, and it continues to be a billion dollar industry to this day.  The minerals mined in Canada include gold, silver, platinum, iron, copper, nickel, diamonds, potash (potassium-bearing minerals), and many others.  In 2014, over $35 billion in minerals were harvested from Canada.  These minerals range from precious minerals like gold and diamond, to the gravel and cement used in everyday life.  

Canada has a variety of both minerals and rocks, as well as some of the oldest rocks in North America.  An area know as The Canadian Shield is made of granite, and contains fossils of bacteria believed to be over 2 billion years old.  The Shield is 1.7 million square miles, and is one of the most mineral rich areas on the planet.  It is the largest area of exposed rock from the Precambrian geologic era 500 million years ago.  Many parts of this granite plateau are covered by either forests and wildlife, or a layer of snow and glaciers in the northern regions.

While many of these mining operations have been going on for over 100 years, I was surprised to learn that the discovery and mining of Diamonds in Canada was a relatively new operation.  While gold has been mined in Canada since the 1800's, the first diamonds in Canada were discovered in 1991.  The Canadian diamond industry has risen to be 3rd in the world, and has received praise for its ethical practices regarding environmental, authenticity, and labor standards. There are many small mining towns throughout Canada, many Canadian citizens support the local diamond and mineral trade.



Sources : http://www.nrcan.gc.ca/mining-materials/publications/8772
                http://geology.com/articles/canada-diamond-mines/
                http://www.canadianshieldfoundation.ca/?page_id=39

Hazards, Disasters and Catastrophes:


A Natural Hazard is a natural process and event that has the potential to threaten human life and property.  The process and the events by themselves are not a hazard, but they become a hazard due to human presence on the land.  These events include earthquakes, volcanoes, floods, fires, hurricanes, and tornado.

A Disaster is a hazardous event that occurs over a limited time span, within a defined area.  There are 4 criteria for a Natural Disaster: 1) 10 or more people are killed, 2) 100 or more people are impacted by the process, 3) a state of emergency is declared, or 4) international assistance is required.  If any one of these applies to the process, the event is considered to be a "Natural Disaster."

A Catastrophe is a massive disaster, that requires a considerable amount of time and money to recover from.  For example, the damage from Hurricane Katrina is still evident and the recovery continues almost 10 years after the process.