A major earthquake that lasts for five seconds is destructive and deadly. When it gets to five minutes, words like 'cataclysmic' and 'apocalyptic' start to come into play. How about five months?!
Well, according to GeoNet, New Zealand's information source for earthquakes, volcanoes and tsunamis, the capital city of Wellington has been going through a magnitude 7 earthquake that started in January and continues to this day!
As we know, an earthquake happens when the Earth's tectonic plates shift, usually diving underneath one another or slipping past each other. Typically, it all happens in a matter of seconds or, in some of the bigger quakes, minutes. That's a lot of energy being released all at once; a magnitude 5 quake like the one earlier this month in Ontario and Quebec releases about as much energy as 200 tons of TNT. The infamous magnitude 9 quake off the coast of Japan in 2011 had the power of nearly 100 megatons of TNT. It's not hard to imagine why that much energy, unleashed over a matter of minutes, is enough to destroy... well... pretty much anything.
The magnitude 7 earthquake that's been going on in New Zealand has the power of 200 kilotons of TNT, but with one important difference — the same amount of energy is being released over the span of, thus far, five months. An earthquake, but in super slo-mo.
This 'slow-slip' quake is called a Kapiti event or a Kapiti slip, and this isn't the first time it's happened.
"We started recording with the GPS network in 2002, and since then this is the third Kapiti event we've seen," said Geonet scientist Caroline Little, in an interview with New Zealand's 3 News. "Both of the previous two have lasted around the year mark. Interestingly it's occurred every five years — 2003, 2008 and then this one in 2013."
The movement from this quake is roughly 40 kilometres below ground, which is not the deepest earthquake (that's more like around 600 kms down), but it's happening over a distance of about 100 kilometres, from Kapiti to Marlborough.
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These quakes can happen in other parts of the world, too. The west coast of North America — specifically along the San Andreas fault in California and the Cascadia fault that stretches from northern California to the northern tip of Vancouver Island — sees them, and they've been recorded in Alaska, Japan and Mexico as well.
It's a popular saying that "it's the quiet ones you have to watch out for," but with these powerful 'silent' earthquakes, we're just going to have to hope that's not the case.
(Photo courtesy: Getty Images, GeoNet)
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