local sustainable bldg materials and methods?

[dobanion]

See my attachment. I pondered doing something like that, but with lava rocks. So the bulk of the wall is still lava, free material, and it looks cool, but backed with steel reinforced concrete.

I have a 6ft tall circular outdoor shower made of stacked lava rocks, but I wouldn't trust it to last during a 7.0+ quake. It took a 5.8 ok.