Chile Forum

There is no real system for predicting earthquakes, all models developed by super computers of Japan and LA haven't found a pattern with out major floors.

However earthquake prevention that is a important thing, and having a trench around your property is proven to work. One of my work colleagues lives in Christchurch, New Zeland, which is hit by a lot of earthquakes it seems, and he has a natural trench on one side, and a large drainage ditch built for the freeway that runs behind his house on a joining side, the earthquakes epicentre are from the corner which have the trenches, and it has meant his property is one of the few that have had near to know damage in his area over the last year. His brothers family now live with him due to loosing their home.

The vibration of the earthquake shock wave must have a medium to travel through, the shockwave will pulse out, in a similar motion sound does. So closer you are to the trench, better protection you have. Its important to get the graiant right on the trench, too deep may cause instability of the bank, too shallow it won't reduce the shockwave as much.



Building trenches on all four sides may counter this, just creating the effect of being ontop of a small apartment block where the shockwave bounces up, defenetly try and think of which direction the epicentre is most likely to be, if it is possible.

I'm sure there must be information out there from an earthquake engineer, rather then my knowledge as ship structural/mechanical/electrical engineer. Although we have similar effects from the pounding of ships in bad weather, and transmitted stresses.

yea, there's so many factors that go into an earthquake, it can get a bit brain numbing if you try to too specifically account for them all. the thing i like about the base isolation approach is the disassociation of the building from the ground. i mean, the ideal earthquake proof house, would be one that floats in the air, so the simpler and closest you can come to approaching that, the better.

i think someone mentioned using piles with isolators on top, speaking with some engineer family of mine, they tend to think that would be the best way to do it as well. they said slabs are typically chosen due to cost and ease of installation in most locations, but pilings usually make the most sense in seismic ground. that study i posted the name of came to the same conclusion. there was also a guy in california who did the same thing (using hydraulics though)... look him up under Randolph Langenbach at conservationtech with the "damped sway foundation system".

seeing the same thing as you admin with these studies, you need to have some mass on top of isolators for them to perform reasonably well. lightweight wood houses don't have enough weight to do much displacement. put up dry stack on a steel frame base on pilings and i think you could probably get some decent magic carpet ride.

speaking of commercial solutions, i wonder how expensive they actually are? there's a company i'm looking at (dynamic isolation systems), that sells LRB's in sizes from 12" to 60" in diameter. the lower end of that scale could potentially be reasonably well priced. although their site looks like they're preferred by larger projects, one of their special projects was a small data center in costa rica... and by small, i mean, it was housed inside a small shipping container. never know, we might not need to reinvent the wheel.

For 'floating houses', houses on rollers/free moving, I would look into Japans house designs. I'm surprised the apartment blocks aren't already upto earthquakes standards? What was the richter in santiago of the last big one? I have only seen superficial damage to plaster board, no structua damage to the two blocks i've been in.

Yes there is a lot of factors, but most structures are effected by a lot of elements, its the complexity and only partial knowledge of the structure that is the problem, when you test a house, or ship or jet engine for stability and integrity under different circumstances, you have to model the entire thing, material specs, size, position and shape, all take effect. With earthquakes your 'model' is actually the entire planet, and theres no way of measuring all the different types of material, temperature, viscosity, shape, strength etc. of it, as it is we still struggle to find out where oil is without spending, in Shells case, 10 billion USD a year on exploration. Like most things in life, better to plan for the worst, rather then chance it.

Brad Pitt's Make it Right Foundation has been using an interesting foundation system on the houses they have been building in the Lower 9th.

Basically they are taking treated telephone poles (the wood ones you see in North America, not the concrete ones in Chile) and driving them into the ground. Then they lay down rebar and pour grade beams and build on that for lateral stability. Seems like an interesting approach and from what I have found it is supposed to be fairly good in earthquake zones.

It could probably be done in reinforced concrete fairly easily, but boring the holes and the rebar work might be prohibitively expensive for most.