Tuesday, September 04, 2007

Earthquakes in SoCal

There was an Earthquake in Southern California last Sunday.

To many of you this probably sounds like a common occurrence, but we actually felt this one in Huntington Beach. I haven't felt any earthquakes for years down here, and the next day there was a smaller one near the same area.

I'm pretty well prepared for earthquakes or interruptions of services, but this got me a little bothered. I started looking at a site that tracks earthquakes and was surprised to see quite a few fair sized earthquakes happening in southern California.

I was ready to get worried, but then I remembered that I'm a bit sensitive to things like this, and decided I should take the time to really crunch the numbers and figure out if there's really something to worry about.

A few crunchy hours later, I could find nothing out of the ordinary, and left with the same conclusion I had drawn prior to my study; We're overdue for a big one.

This is, of course, no secret. We've been overdue for quite some time, and everyone living here still has that notion somewhere in the back of their minds. I just wish they'd have the notion somewhere in their cabinets in the form of water and canned goods.

But, since stats are always open to interpretation, let me relate to you the findings of my short study of the numbers...

  • We only seem to have significant records from 1998 to present day (wtf?)
  • 1999 had a lot of fucking earthquakes (80 for the year, when the average for 1998-current was 29.7)
  • In 1999 there was a 7.1 in Joshua Tree area (Hector Mine Earthquake), which was in the middle of fucking nowhere, which resulted in no damage or loss, which was probably why this was the first I'd heard of it.
  • Of earthquakes 4.5 or greater we've had 2, previous years have been 2, 9, 2, 5, 4, 4, 23 (1999), and 3. Nothing big here.
  • Of earthquakes 5.5 or greater we had a 5.7 in 2002, a 5.8 in 1999, and the Joshua Tree 7.1 in 1999. It's been a while.
  • Joshua Tree aside, we haven't had anything over 5.8 since Northridge in 1994.
  • The only quake larger than Joshua Tree was Landers (south of Joshua Tree along the same fault line) at 7.3 This area seems prone to tectonic pressure...
  • Since Northridge, I can't find any quakes greater than 5 recorded on the coastal faults of southern California.

Conclusion: WE'RE ALL GOING TO DIE!!!

But seriously, I haven't found the recent shake-up to be anything but par for the course for southern California. The only difference was, it happened to be in a place I could feel it. It still seems pretty clear that our faults are overdue for a magnitude 6 quake, but hopefully all that heavy shaking going on in the Joshua Tree area is relieving pressure on our weary faults.

I'm still using it as an opportunity to talk to friends and coworkers about getting their earthquake kit ready. What I don't tell them that it could also be used for human-created disasters. They can figure that out on their own. Though sometimes I can't help but drop a hint like mentioning that my "earthquake" preparedness kit contains potassium iodide.

1 comment:

Josh said...

One thing that I'll always remember from my geology classes is the historic frequency of Earthquakes is pretty close to being right in all recorded incidences. You guys up in LA had Northridge in '94 - down in SD, we haven't had a 6+ for 140 years. Talk about overdue...and when Rose Canyon lets go - well, it was nice knowin' everybody.

The USGS site is always running on my desktop, and I check this one every morning for stuff in that "other" category.