Marc G. Fournier wrote:
>
> Is there a higher then normal amount of earthquakes happening
> recently? haiti, japan just had one for 6.9, there was apparently one
> in illinos a few weeks back, one on the Russia/China/N.Korean border
> and now Chile?
Random events come in bunches - something I always stop to remind myself
of whenever there is a sudden bunch of quakes, celebrity deaths, plane
crashes, etc. Especially with relatively unusual events like
great-quakes and plane crashes, it can be tough to see if there is any
signal in the noise - a job I have to leave to experienced statisticians.
The world averages one "great" (8+) earthquake/year which, of course,
means some years like 2008 have none but 2007 had four. 7-7.9 like Haiti
or our own Loma Prieta quake are far more common averaging ~17/year.
Haiti is a catastrophe not because the quake was of unusual size (it
barely made it into the 7-7.9 category and released less that 1/15 the
energy of the Chile quake) but because the hypocenter was both shallow
and fairly close to Port-au-Prince combined with terrible construction
standards and virtually non-existent emergency-response capabilities in
Haiti.
Some general quake stats/facts are here:
http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php
Cheers,
Steve