[kabouseng]

Lava is molten rock. Concrete blocks are rock.

[ceejayoz]

So is the ground it comes out of and runs over. It doesn’t instantly melt rock it comes into contact with.

[ygra]

Also from the blog:

> Benedikt Halldórsson of the Met Office says houses are not designed to withstand lava flow.

> »... You can expect the walls to give way from the load, and the heat in the lava is such that it burns everything in its path.«

Apart from the heat, since it's molten rock it also has considerable mass, and the lava flow continues pushing from behind.

[jon_richards]

One weird realization I had is that lava is over three times as dense as water, so if you tired to “swim” in it, you’d basically just sit on top.

[sixothree]

I'm not really sure what you mean by this. But I'm guessing that you really have no clue what would happen.