Canada and the World
Current Events with a Canadian Perspective
Last update
19 November 2010
Waiting for the Big Earthquake
Massive earthquakes are not just something that
happen to people in distant countries; Canada’s west coast is a hot spot of seismic activity
The Earth’s crust (called the lithosphere) is divided into plates. These continent-
The rock that forms the asthenosphere is solid enough to support the lithosphere, but it’s also squishy enough to flow. It doesn’t flow in a way we can recognize, like water. It flows on a geological time scale – in movements measured by metres in centuries.
Plate Tectonic Movement
As the asthenosphere moves so do the plates riding on top of it in a process called tectonics. They move quite slowly. Over a year, the movement is scarcely noticeable. But, the progress is continuous and relentless. It adds up over decades to be quite significant. The fastest moving plates might travel more than eight metres in a hundred years.
With a plate the size of a continent bashing into another plate, even at these slow speeds, there is a massive amount of energy involved. So, dramatic things happen.
The Indo-
If a Ferrari crashes into a brick wall there’s bound to be a lot of crumpled metal
and the hood often forms a peak. 
Same thing with geological plates. When the Indo-
The crash slowed the Indo-
Plates Grind Past Each Other
The Himalayas were the result of a head-
The two plate edges coming into contact don’t glide as a curling stone does over
ice. It’s more like two pieces of heavy-
Tectonic plates might lock together for a time, but there is still the relentless force of continents pushing the plates. Eventually, the pressure is so great that the friction between the plates is broken.
The plates lurch forward in a great release of energy – that’s an earthquake. This
sudden motion usually occurs along a fault or fracture – an area of weakness in the
Earth’s crust. One way to visualize this is to slowly bend a stick until it breaks.
The stick bends fairly easily, up to a certain point, until the stress becomes too
great and it snaps. The vibrations felt when the stick breaks represent the sudden
release of the stored-
Earthquakes are not Rare Events
Earthquakes are happening almost constantly. Most of them are small and pass unnoticed by all but a few geologists. Occasionally, however, there’s a big one. The result, if it hits in a populated area, is massive destruction and loss of life.
Where the earthquake happens determines the scale of destruction. Quakes that happen near the surface cause the most damage. Quakes that occur hundreds of kilometres deep are less destructive. And, of course, distance from the focus of the quake is a major factor. The heart of the earthquake is called the epicentre and being as far away from this as possible is a good plan.
Earthquakes frequently happen beneath the surface of the sea. If such a quake is big enough it can start a tidal wave, known as a tsunami. This is what happened on Boxing Day 2004. A massive undersea earthquake hit off the Indonesian island of Sumatra.
The power of this event was huge; one estimate suggests it was similar to the total amount of energy used in Canada in three and a half months; all of it released in a few seconds. This set off a massive movement of water. By the time this wall of water reached the Indonesian province of Aceh it was between 24 and 30 metres high.
Destruction was total wherever the tsunami came ashore. The death toll was in the neighbourhood of 230,000.
Hotspots for Tremors
Most of the world’s earthquakes occur along what is called the Ring of Fire. This
is a 40,000 km-
The Ring of Fire title comes from the close relationship between earthquakes and
volcanoes. Where plates rub up against each other cracks in the Earth’s crust are
likely to appear. Molten rock from the planet’s core pushes up through the cracks
to create volcanoes. 
More than three quarters of the world’s active and dormant volcanoes
are on the Ring of Fire, such as Krakatoa, Indonesia, seen here during a mild eruption
in January 2009.
The floor of the Pacific Ocean is divided into several plates. The largest one, the Pacific Plate is moving northwest relative to the plate that holds North America. It’s motoring along at seven cm/year; that’s about the same speed at which a human fingernail grows. There are several, smaller plates on the eastern side of the Pacific and these have created havoc on the west coast of our continent.
The “Big One” will Come
There are an average of 18 major earthquakes and one gigantic one each year. Canada has experienced one monster quake in the Queen Charlotte Islands in 1949. There have been several major to moderate earthquakes – Charlevoix (1925); Grand Banks (1929); Temiscaming (1935); Saguenay (1988); Quebec City (1997); Victoria (1999).
In February 2006, scientists warned the people of British Columbia that a catastrophic earthquake was imminent. It didn’t strike, but one day it will. When it does it will be disastrous.
In downtown Vancouver, pedestrians will be showered with glass falling from office towers. Bits of masonry and other heavy materials will shake loose and plunge to the ground. Some entire buildings will collapse.
Transportation will come to a standstill. The streets will be clogged with debris and vehicles; some bridges and tunnels will cave in. Telephones, hydro, and water supplies will probably be shut down. Banks, gas stations, and food stores will be out of action
Natural gas supply lines will fracture and this will trigger fires. A massive, salt-
There will be little hope of emergency services providing any help in the first hours. Although fire and ambulance stations have been strengthened, some fire trucks and ambulances and their crews might be trapped under their own flattened garages. If the hospitals haven’t been damaged their emergency rooms will be completely overwhelmed by casualties.
For the first few days, most citizens will be on their own. Eventually, help will arrive from outside, but until it does life for the quake’s survivors will be extremely difficult.
It will take decades to completely rebuild the city. Which begs the question of, why bother? Vancouver will certainly be destroyed again when the next giant quake comes sometime in the next 500 or so years.
Earthquake Predicting very Difficult
The failure of the “Big One” to show up in 2006 highlights the difficulty of predicting earthquakes. Scientists can say that a fault line is under stress, but they can’t say precisely when the two sides will break free. They can say only that there’s maybe a 65 percent probability that an event will occur in, say, the next five years.
(Some animals do appear to sense that an earthquake is about to happen and start
to get agitated and nervous. They may pick up low-
Being in an earthquake is a frightening – make that terrifying – experience.
Bronwyn Davis lived through a major quake (7.9) in Peru in August 2007. She wrote an eyewitness account for the BBC: “There were two massive shocks, which lasted for some time. It felt like around two minutes in total with a short break in between.
“Usually you don’t feel a tremor when outside, but we were outside and the pavement was rippling. We fled to the park where the ground continued to move under our feet. What was even more frightening was the roar of the quake coupled with the sky lighting up.
“It was surreal. It felt like we had stepped onto the set of a war movie. There was a real sense of fear on the streets.” Ms. Davis was 145 km away from the epicentre.
Image credits
Sunil Hariyani
Flydime
“Peru Quake: Eyewitness Accounts.” BBC News, August 17, 2007.
“Talc-
“Haiti Earthquake.” BBC News, July 7, 2010.
© Canada and the World, October 2007
Updated July 2010
All Rights Reserved
NOT IF BUT WHEN
Vancouver and Victoria are sitting in a danger zone. The Juan de Fuca Plate is sliding under the North American Plate from Vancouver Island to northern California.
The process is called subduction and it tends to produce some of the nastiest quakes.
The Juan de Fuca Plate is chugging along at between two and five cm/year. It’s about 45 km deep under Victoria and 70 km deep under Vancouver.
Scientists believe the plates are currently stuck together.
This is where we visit Earthquakes Canada in Ottawa to get the bad news. “At some
time in the future, these plates will snap loose, generating a huge offshore subduction
earthquake -
The geological record shows the region has suffered a giant quake, on average, every 500 years or so. The immediate question that springs to mind is “When was the last one?” The answer: 26 January 1700. Phew – safe for almost two more centuries. But, you can’t set your watch by these events.
The scientists say a great earthquake will definitely hit the West Coast. It might not happen for years, but it might happen tomorrow.
In an effort to get a bit of advance warning a project called Neptune Canada has
just started. In August 2007, the venture began laying 800 km of fibre-
All the data collected by this network will be fed back to a shore-
The plates that form the Earth’s crust are called “tectonic” from the Ancient Greek
word “tekton” meaning builder. Canadian geologist John Tuzo Wilson (1908-
WAITING ON
SAN ANDREAS
The San Andreas Fault runs for 1,300 km, through California. The Pacific Plate moves northwest and grinds against the North American plate. The line of contact is the San Andreas Fault.
At the northern and southern ends of the fault there is a “stick and slip” movement.
The plates grab and hold each other and then violently tear apart. One such fierce
separation was the San Francisco earthquake of 1906 that reduced the city to rubble.
However, in the middle section of the fault the two plates creep past each other with little drama. A 2007 study published in Nature says the reason for the relatively peaceful zone is talc. This soft mineral has been found about three kilometres below the Earth’s surface and it acts as a lubricant.
But, tipping truck loads of baby powder down the southern and northern ends of the San Andreas Fault won’t delay the next “Big One.”
In October 1989, a 7.1 strength earthquake happened about 80 km south of San Francisco. It caused $6 billion worth of damage and killed more than 60 people. Five years later there was a 6.6 shaker in Northridge, an area of Los Angeles. This caused roughly the same death toll but about $30 billion in damage.
But, these are minor events compared to the “Big One.”
Scientists say it is most likely to occur in the southern section of the San Andreas Fault. They turn up roughly once every 150 years. The last one was in 1857. So, it could hit anytime.
In July 1976, without warning, a magnitude 7.8 earthquake struck the city of Tangshan
(above) in China, killing 242,769 people and destroying 90 percent of the city’s
buildings. But the country’s—and the world’s— deadliest recorded earthquake happened
in 1556 in central China. It hit a region where most people lived in caves carved
into soft rock. These homes collapsed, killing an estimated 830,000 people.
Canada Mortgage and Housing Corporation estimates that a major southwestern B.C.
earth-
UN Development Program
The massive earthquake that hit Haiti on January 12, 2010 took the lives of 230,000
people. The death toll was particularly high because the poor quality of construction
on the poverty-