Thread: The Science of a Seismic Storm

Several factors came together to make Haiti's earthquake the most devastating seismic shock to hit the country in two centuries - ranging from sheer magnitude to sheer poverty. In purely scientific terms, the best comparison was the Loma Prieta earthquake that shook the Bay Area during the 1989 World Series. But the tragedy in Haiti isn't purely scientific.

The death toll seems certain to rise into the tens of thousands in the wake of Port-au-Prince's magnitude-7 quake, compared with a death toll of 63 after the magnitude-7 Loma Prieta quake. The difference clearly has to do with the woeful state of infrastructure in Haiti, the Western Hemisphere's poorest country.


The science of a seismic storm - Cosmic Log - msnbc.com

There are so many factors to consider how dangerous an earthquake can be and this article explained them, from how shallow the quake is to the building codes to what time the main shock hits. This quake had a multitude of everything going bad: the time period when people were working in buildings that collapsed (and many of them were not up to any decent earthquake code), the strength of the quake, etc.

Much of the damage in the 1989 quake was in the marina area (I think that's what it was called) because of liquidifaction. If you drove around the San Fernando Valley right after the 1994 quake hit here, you can see much of the damage by driving along the Los Angeles River bed as the ground tends to be soft. That's why I was able to feel four shakings that early morning and not just the three ones that happened...the ground kept shaking. We were also fortunate that despite the shallowness of the quake to the surface, that it hit at 4:30am so that barely anyone was in the stores and parking structures that collapsed (after their reopenings, many stores put up photos of the damage). The biggest loss of life in just one building was one apartment building in which the third and second stories collapsed onto the first story completely and those on the bottom floor didn't have a chance. By contrast, the 1989 quake struck during rush hour and many were trapped under that bi-level highway that collapsed.

One janitor was caught in the collapsed parking structure at the Northridge Mall, but was rescued by the LAFD using a "balloon" type structure to help lift the roof enough for the rescuers to get him out without getting trapped themselves. When the rescue crews in Haiti are digging out people (hopefully alive), they will try to keep the structures from collapsing even more, just in case there are others underneath. There will be hundreds of aftershocks, so that will be making their job even harder. (In contrast the 2001 Olympia earthquake that hit Washington State didn't really have aftershocks.) It's a dangerous duty so it's worth praying for their safety too.