By Bob Groeneveld
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Every time there鈥檚 an earthquake of any significant proportion within a few thousand miles of us, we are reminded that the 鈥淏ig One鈥� is going to hit us one day.
In fact, the Big One warnings are trotted out even when there鈥檚 a temblor on the other side of the world, if it shakes hard enough and causes enough damage to titillate the fear mongers.
The Big One could even hit us 鈥渟oon,鈥� we are told by breathless television news anchors who are, statistically speaking, statistically ignorant, and rarely bother to mention that, geologically, 鈥渟oon鈥� in this case could mean maybe possibly conceivably perhaps within 50 to 200 years.
The Big One is the rather cheerful moniker appended to an anticipated event of magnitude 9.0 or greater.. That鈥檒l do more than rattle your windows and knock a few pictures off your wall, which is what you can expect from a quake around 4.5 to 5.0 range.
Each order of magnitude relates to about 33 times the amount of energy released by an earthquake. So you multiply a barely noticeable 3.0 quake by 33 to get a 鈥測es, I definitely noticed something鈥� 4.0 quake. Multiply that by 33 to get a window-rattling 5.0, and multiply that by 33 to get a building-damaging 6.0. Now multiply that by 33 and again by 33, and once more by 33 to reach our magnitude 9.0 Big One 鈥� that鈥檚 about 1.3 billion times as powerful as what you鈥檙e feeling when you wonder whether or not that was an earthquake.
It doesn鈥檛 happen often. And it doesn鈥檛 happen just anywhere.
We are among the few chosen people on this planet who have the honour of potential obliteration by a megaquake.
In fact, only four temblors of Big One magnitude have been recorded since there have been instruments capable of recording them. The biggest was in Chile, a whopping 9.5 quake in 1960, which actually had a measurable impact on the rotation of the earth.
The last time there was a megaquake near our neighbourhood was when a 9.2 shaker rattled Anchorage, Alaska, for several minutes in 1964, and sent a tsunami down the coast, washing over Port Alberni, where I was living at the time (though I was well out of harm鈥檚 way 鈥� property damage was severe, but there were only minor injuries and no deaths in town).
Before that, there was an estimated 9.0 Big One generated right here in January of 1700, which sent a tsunami across the Pacific Ocean and wiped out villages in Japan.
The next Big One could send out another such wave 鈥� possibly 20 metres high (that鈥檚 60 feet, for the old fogeys out there who still refuse to go metric 鈥� just about twice the height of the streetlight that annoyingly shines in your bedroom window at night).
But it鈥檚 very unlikely that anyone reading this will be alive long enough to die when it comes.
So don鈥檛 let them scare into an earthquake preparedness plan to get ready for the Big One that鈥檚 not statistically likely until at least the next century.
Instead, you need to have an earthquake kit prepared for the Little One of 6.0 or 7.0 magnitude that has a real probability of interrupting our lives sooner than a geological 鈥渟oon.鈥�
