So apparently there was a 5.8 magnitude earthquake today with the epicenter being about 120 miles east of San Diego…I guess there are no reports of damage, which is great. Anytime I hear about an earthquake that is above 5.0 in magnitude I always perk my ears up because I have been told that this is the magnitude at which you would usually start seeing damage–possibly both structural and non-structural. It seems like we had a similar sized earthquake in Yorba Linda California in the summer of 2008 and nothing came of it. But we are talking about Southern California here. Southern California has done a pretty decent job eliminating and mitigating their unreinforced masonry structures.
I am pretty curious about Mexico though. The article claims that in the border towns of Mexicali and Calexico they don’t have any buildings that are more than 3 stories high? That’s really delightful, however–unreinforced masonry structures can kill people even if they are only one story! As unreinforced masonry tends to crumble outward, even people standing or walking just outside the building could be hurt or even killed!
Maybe I am delusional here, but Mexico isn’t exactly a “developed” country, so I would have expected some damage down there. Having been to Tijuana once in my life as a child, I can’t remember what everything was like down there. Something tells me they are probably not on the cutting edge of mitigation strategies down there, though. Someone please correct me if I am wrong. Are all these border towns flush with cash for earthquake mitigation? Are their structures well built?
Who knows, maybe this has more to do with attenuation and such. The types of soil, maybe. But hey, I am no seismologist.