On Tuesday, a powerful 8.8 amplitude earthquake shaken the area around the Kamchatka peninsula in Russia, causing Tsunami warnings worldwide. From Hawaii to Japan and on the coast of British Columbia in Chile and Australia, people have been warned that high waters could flood their coasts.
Many people remember the fatal tsunami the day after Christmas 2004, which followed an earthquake of magnitude of 9.1 off the coast of Sumatra, in Indonesia. More than 280,000 people died and more than a million people were moved to South Asia and East Africa.
Another memorable and tragic and tsunami earthquake was the Tohoku event in 2011, which forced the closure of the Fukushima nuclear power plant in Japan and killed more than 15,000 people.
Obviously, tsunamis occur, but how often and how dangerous can they be? Here are some tsunamis facts.
Large waves were seen on Wednesday when they reached the Hokkaido coast in Japan following a powerful coarse earthquake in Russia.
What is a tsunami?
The answer is less simple than some imagine it.
Most people tend to consider a tsunami as one big wave that reaches a coast. But a tsunami is actually a series of waves, generated by the displacement of water in the ocean. It can increase water levels by centimeters to tens of meters and can wash houses, buildings and people.
Tsunami waves move in all directions and can move through an entire ocean basin – as we saw with the Kamchatka earthquake on Tuesday, which traveled from the North Pacific to the South Pacific to New Zealand.
And they don’t only stay on the coast. They can browse rivers and berries and can last several hours or a few days as they swing in an ocean basin.
The tectonic plates of the earth move slowly – about nine centimeters per year, slightly faster than the nails develop. This movement can trigger powerful earthquakes. Seismologist John Cassidy explains science behind earthquakes and why they can lead to tsunamis.
Katsu Goda, Associate Professor in Earth Sciences at Western University and Canada Research Chairman in Multi-hazard Risk Assessment, said that it was as if you put your finger in a bowl of water, you would see small ripples, not just one wave.
What causes a tsunami?
Eighty percent tsunamis are generated by earthquakes, but it is not their only source.
They can be caused by landslides above and under the ocean. Rarely, they can be caused by atmospheric changes. These are called meteotsunamis. In fact, we think we performed on Lake Supérieur in June near Thunder Bay, Ontario.
Shuniah, Ontario, Resident Alan Auld submitted this video of the water levels fluctuating in front of his house. Scientists say they think that video shows a meteotsunami, which is a type of large wave that can be caused by atmospheric pressure changes.
Submarine landslides can be triggered by relatively average earthquakes, Goda said. These underwater landslides can extend over hundreds of kilometers, causing a large movement of water which spreads upwards to cause a tsunami.
It is also important to understand that even if an earthquake has an epicenter, it actually occurs over a hundred kilometers or more.
When they occur in the ocean, it’s a lot of displaced water.
To what extent are they common?
Tsunamis – especially adults like Sumatra and Tohoku events – are rare, said Goda.
“We think those [occur] At least a few hundred years to a thousand years old … for a place, “he said.
According to the global tsunami database, dangerous tsunamis occur about twice a year. Larger tsunamis that cause damage or death at more than 1,000 kilometers occur approximately twice a decade.
Is Canada at risk?
When Tsunami warnings on Tuesday was issued, they included a large part of the British Columbia coast.
The province is not unrelated to the threats of earthquakes or tsunamis. Indeed, the border is called the Subduction Zone of Cascadia and extends 1,000 kilometers from the north of the island of Vancouver to northern California.
The earthquakes that occur in the Cascadia subduction zone are called megathrest earthquakes, with the rupture area seated in the west of the island of Vancouver. This is the source of the “big” potential for British Columbia, an earthquake of new or more magnitude.
“The Cascadia subduction area, known as” The Big One “, is the one for which we have to be prepared,” said Goda. “If that happens, there are things similar to Tohoku or Sumatra.
Brent Ward, co -director of the Center for Natural Hazards Research, says that an international network is in place to determine the risk of a tsunami, sometimes in a few minutes after an earthquake. Tuesday, British Columbia published several tsunami opinions after a large earthquake in the Pacific basin near Russia.
According to Natural Resources Canada, these earthquakes occur about every 200 to 800 years. And if there were to be “the big one”, there would be only a gap of 15 to 30 minutes between the earthquake and the first waves of tsunami.
But there is also the east coast.
Although not as active as the “Ring of Fire” of the Pacific Ocean – an area in the form of a 40,000 -kilometer horseshoe known for its seismic activity – there is a fault in the middle of the North Atlantic Ocean.
In fact, there was an earthquake of magnitude 7.4 in November 1929 which caused a landslide deep in the ocean, which led to a tsunami which generated waves of three to seven meters in Nova Scotia. In Newfoundland, the waves reached 13 meters.
Goda said that although there is no way to stop a tsunami, it is important to have good warning systems in place.
It seemed to be the case with this last earthquake and tsunami.
“I think it is very difficult to prevent the wave itself, it’s like-in my opinion-enormous energy,” he said.
“I think the only solution is evacuation to save people’s lives. Early alert is therefore important, and tsunami evacuation training is important, and there should be a place where people can evacuate.”
