Resist the 15

After 8 on the Richter scale, the scale does become meaningless. Numbers beyond that if represented at all, do mean: time of shaking. Now lets imagine a multiple shaking quake, with vertical and horizontal wave patterns back and forth. They usually last for 10-35 seconds. A monolithic dome may stay together for that length of time. But when you extend the shaking to 2 minutes, 5 minutes, 15 minutes: any building structure or even large plant (like a tree) will start to come apart at the connections. Even domes that are not welded steel will begin to break apart at the moment of shaking here represented. The only thing that will hold up in those conditions would be a welded dome without moment connections - meaning a molecular bond, or a structure where movement of constant nature is expected.

Now the problem here is wind. We can design a structure to hold up under any possible earth quake (this is not to specify that the inhabitants or the contents will not come apart), but a structure of this type will blow away in a tornado type wind. Basically we want a steel mesh tent for the shaking and the falling ash. But we need, an underground structure for the tornado winds.

Thoughts by Eric

What if we were to build the structure completely underground? That way we wouldn't even have to worry about winds, we would obviously be concealed so we wouldn't have to worry so much about raiders in the Aftertime, and the answer I got from a geologist as far as what's safer, and underground structure, or an above ground structure, was an underground structure. He said the closer to the surface you are the worse it is. So wouldn't it seem logical to just make a structure completely underground?

Thoughts by Peter.

If the duration of the shaking is close to what I think it will be then the ground in many areas will simply become like a liquid and slosh back and forth. One would need something akin to a submarine with ballast so as to stay upright. You wouldn't want to end up upside down. You would not want winding corridors or anything that could break off as this unit gets sloshed or moved around.

An analysis of the weight of the unit compared to the weight of the ground it displaces would need to be done. For as soon as the soil or ground liquefies the unit could conceivably pop to the surface displacing it's weight in soil. Then your back to the surface exposed to wind and flying objects, etc. Not all soil-ground would liquefy. If you built in bed rock then I suspect no problem. If you built it in some of the tough clays found then we get a gray level answer of maybe. Then there is the problem of digging your way out if the entrance gets blocked. Then there is the problem of all the rain and how to keep it out if cracks appear.

Thoughts by Mike

The safest places are easy to configure now: those places which have had almost zero incidence of earthquakes in the past 500 years. The eastern USA Appalachians are a good example as they are a very old mountain chain with very little earth activity. While they will move, they will tend to move with the whole plate like an ice floe in the ocean, but they won't be coming apart.

Thoughts by Eric

If one were building near a tectonic plate edge, then one will get lots of very strong up and down thrusts. If one is say over 1000 miles from the edge of the plate then one gets more gentle horizontal thrusts and very weak vertical thrusts. So part of the answer is what is the minimum distance from the plate edge for safety in an underground structure.

Thoughts by Mike