Sunday, April 04, 2010

A Note on the Baja California Earthquake

The 2010 Haiti Earthquake was 7.0 on the Richter Scale. The 2010 Chile Earthquake was 8.8. The 2010 Baja California earthquake was 7.2.

Since the Richter Scale is logarithmic, the Baja California was about twice as powerful as the Haitian Earthquake but about two-hundred fifty times smaller than the Chilean earthquake. 230,000 were killed in Haiti but there have been only 432 confirmed dead in Chile. The clear lesson is that building engineering quality is the key factor in casualties from an earthquake.


exuberance said...

No. The clear lesson is the quake magnitude is but one input to estimating casualties. Building codes, quake depth, geology, and population density where the shaking happens are just or more important. The quake North Mexico quake was in an amazingly remote and unpopulated region, the shake map shows it's worse effects barely reaching any populated area and then only a very small town. The quake in South America was extremely deep and it's shake map shows the effect spread out thinly over a vast region.

Catholicgauze said...

The depth and position did play a part, no doubt. Even then the Chilean earthquake was about 500 TIMES as powerful as the Haitian one. If Chile had Haitian like building standards then the death toll would be much higher. Not as high as in Port-au-Prince due to position, depth, etc. but still much, much higher. The 1985 Mexico City earthquake was a great deal away from DF but still killed around 40,000 due to bad building standards.

sgenius said...

Mexicali, the "small town" that Exuberance refers to, is my hometown. Capital of Baja California State, It happens to harbor almost a million inhabitants and is an important commercial and industrial center in the Mexican Northwest (although smaller than Tijuana).

Mexicali has been always aware of its high seismicity and thus, there's an adequate prevention culture in the community. Tall structures are uncommon, and the buildings are made from light materials. Thus, the city was struck, but not as heavily as Haiti.

I concur, however, with Catholicgauze's point about poor building standards, and exuburance's mention of the quake depth being an important factor also.

exuberance said...

sgenius, I hope your family is fine. But, actually I was referring to Guadalupe Victoria, which is the closes thing to the quake on this map:

That said, that isn't the shake map I recall; the one I recall didn't show the involvement of the entire mountain range.

So point taken, Mexicali is clearly the nearest significant population center to the quakes effects.

That said, non of the red portions include populated areas while most of the Haitian quake's shake map does.

By the way, this photo is amazing:

sgenius said...

My family is fine, fortunately, thank you! :)
I stand corrected; your point is valid. Guadalupe Victoria is a small town - and it was heavily struck.
Thing is, since somebody at NPR reporting about the earthquake talking about Mexicali as "a small town", I developed some... resistance to that term :D

However, your comparison to the Haitian earthquake in terms of impact over populated areas is totally true. I think we were fortunate this quake happened over the Laguna Salada fault - there is another (although less active) fault that reaches Mexicali proper...