Wednesday, March 3, 2010

Earthquakes in AK



We have quite a few small quakes here in Alaska. Here is the activity in the last 48 hours. Some days we have them close to Kodiak. I noticed a 4.0 a few months ago because the pendulum on the Grandfather clock was moving at right angles to its usual swing. Some claim they felt the ground move; I didn't.

Chile has had the largest quake on record in 1960 at 9.5, followed by the one in Sumatra in 2004 at 9.4 . Ours in 1966 was the next strongest at 9.2 ( I had previously said 9.4, but my source was just wrong; Ican't find that number in other reputable source.) The recent Chile one was 8.8. We've also had an 8.7 in 1965 and an 8.6 in 1957 here in AK. But no one talks much about those.

Like in real estate, its all about location, location, location (and its relation to population). The deadliest one was the 1956 China 8.0 quake which killed 830,000 people. There have been 2 other China quakes killing over 230,00 each. The recent 7.0 Haiti quake is the 4th deadliest at 233,000.

People worry about those that might develop off Northern California to Oregon. According to today's local newspaper, there is an 80% chance of a Megaquake deveoping there within the next 50 years. Fortunately the chances decerease just north of that: only 27% likely to occur off Washington-Vancouver in the next 50 years.

I don't know what the chances of a reccurrence of the 1964 quake might be here in Alaska. But as Doris Day sang, "Que sera', sera'. The future is not ours to see. Que sera'. sera'!"

PS for those who can't get too much trivia into their head: The Richter scale is good till about 7.0. Above that almost all quakes measure about the same. So now they use the Moment Magnitude Scale (MMW or Ms) which separates the strength of the big quakes much better. In any case, a whole number difference means a 10 fold increase on the heigth of the graph and a 32 times increase in the energy of the quake. So comparing a 5.0 vs a 7.0 quakes means 10X10 (or 100X) more movement of the needle on the graph or 32X32 (or 1032 X) more energy released.

Enough for now. Maybe we'll talk about volcanoes some day, another local force in Alaska. But at least we don't have snakes, nor fleas, nor ticks. Aren't we lucky?

1 comment:

Carlos said...

Typo: Our big quake was in 1964, not 1966 (as stated in 2nd paragraph). Never could type.