[Sca-cooks] small earthquakes
Sharron Albert
morgana at gci.net
Sat Dec 30 18:38:51 PST 2006
>Urtatim commented:
>
><<< (boom, rattle, rattle, rattle)
>Sh*t, that's the third earthquake in the past 3 or 4 days, all the
>same magnitude and with the epicenter just a couple miles from my
>house.
>
>Stefan replied:
>
>I'm sorry to hear of your discomfort. But I suspect that these small
>earthquakes are actually good, since they let off some of the
>building pressure. These small quakes do minimal damage, even if they
>are disconcerting. However, if the pressure between the sliding
>tectonic plates is not occasionally relieved, it continues to build
>until it overcomes the friction holding the plates back and that is
>when you get the much bigger 6, 7 and 8 magnitude (on the Richter(?)
>scale) quakes. Those are the ones that do major damage and in which
>people get hurt and killed.
>
On the other hand, small quakes can be harbingers. We had a bunch of
smaller quakes in the 3-4 point range in the Talkeetna area strong
enough to be felt in Fairbanks (about 150 miles away iirc) before the
big 7.9 one that rattled the state a couple years ago. I kept feeling
them (after the Good Friday Earthquake so many years ago I'm
relatively sensitive to earth movements), and looking them up on the
Alaska Earthquake page, and noticed the clustering. I actually said
to myself "hum, it looks like something's going on down there." Then
we had one around 5.9 followed by the big one and all the aftershocks
as the major fault line shifted sideways across the state to
compensate over the ensuing months.
So, yeah, mostly small ones are good. But specific clustering should
be watched carefully...
Morgana, in snowing Fairbanks (which will make the skiers happy)
--
Tactics is knowing what to do when there is something to do. Strategy
is knowing what to do when there is nothing to do. --Savielly
Tartakover, GM, quoted in "The Eight" by Katherine Neville
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