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Re: Poor Mojave............etc
Author: mook
Date: 10-03-2015 - 13:10
Bob2 can probably mention some things learned from Dr. Jones, but note:
- There were no freeways around to collapse in 1933 (which wasn't really bad outside of Long Beach-Gateway Cities area anyway) and 1952 (which, again, was some distance from the LA Basin, though widely felt).
- 1971 was for highways and dams what 1933 was for schools: wakeup call and many design changes and fixes afterward (and still ongoing) which greatly strengthen things. Unfortunately (as demonstrated in 1989 Bay Area, 1994 Northridge, and a couple of other shocks causing localized damage) not everything could be fixed, or at least fixed in time for the next shock.
- 1994 demonstrated that the upgrades weren't enough, or that some structures were still waiting for them (does cost money, which comes in drips and drabs not large chunks), though unlike in 1971 nothing fell on the railroad in the 14/5/210/405 interchange area. Hopefully, when 14/5 was put back together (again), some further upgrades were done.
Designers can only work with what's known or discovered at the time something is built, and retrofit for stronger standards developed later is usually difficult and expensive. Retrofit might be done for some highway structures, or dams where survival and continued operation is necessary, and for some other "lifeline" facilities. But once a building is erected it's very difficult to make major structural changes. So there are a lot of buildings that meet older codes (or none) and will probably take significant damage (or collapse, if nothing is done to retrofit) in a future quake.
Many of the papers, presentations, and scenarios from Dr. Jones' groups are helpful in understanding what goes on around LA with regard to earthquakes and other geological issues. If you're interested, they're very much worth reading or watching. She's very good at explaining things so that an advanced degree in geology is not required.
The recent "San Andreas" movie is NOT one of Dr. Jones' scenarios!
- There were no freeways around to collapse in 1933 (which wasn't really bad outside of Long Beach-Gateway Cities area anyway) and 1952 (which, again, was some distance from the LA Basin, though widely felt).
- 1971 was for highways and dams what 1933 was for schools: wakeup call and many design changes and fixes afterward (and still ongoing) which greatly strengthen things. Unfortunately (as demonstrated in 1989 Bay Area, 1994 Northridge, and a couple of other shocks causing localized damage) not everything could be fixed, or at least fixed in time for the next shock.
- 1994 demonstrated that the upgrades weren't enough, or that some structures were still waiting for them (does cost money, which comes in drips and drabs not large chunks), though unlike in 1971 nothing fell on the railroad in the 14/5/210/405 interchange area. Hopefully, when 14/5 was put back together (again), some further upgrades were done.
Designers can only work with what's known or discovered at the time something is built, and retrofit for stronger standards developed later is usually difficult and expensive. Retrofit might be done for some highway structures, or dams where survival and continued operation is necessary, and for some other "lifeline" facilities. But once a building is erected it's very difficult to make major structural changes. So there are a lot of buildings that meet older codes (or none) and will probably take significant damage (or collapse, if nothing is done to retrofit) in a future quake.
Many of the papers, presentations, and scenarios from Dr. Jones' groups are helpful in understanding what goes on around LA with regard to earthquakes and other geological issues. If you're interested, they're very much worth reading or watching. She's very good at explaining things so that an advanced degree in geology is not required.
The recent "San Andreas" movie is NOT one of Dr. Jones' scenarios!
