Just add several layers of cement all around the area you want to save. Then, it'll either be someone else's problem or lava landberg.

Even still best case scenario would be like a pimple popping internally. There's still something going on below the surface that is not good.

But there would not be that best case scenario with a volcano. It's gonna blow if it wants to blow. Bonus: flying shards of concrete to compound the death and disaster all around.

It's concrete, not cement. Cement does fuck all without water, aggregate and sand. Don't forget your tensile strength in rebar. It's like calling ketchup tomatoes.

We don't do this stuff because of Phineas Gage.

I feel like this is a Veratasium video in the making

The source of all that stuff leaking out is the sea which all our mountains float on.

I remember reading an article discussing the difficulties of re-directing a lava flow. One thing they mentioned was they tried dropping concrete blocks into or in front of the flow, and the concrete just floated on the lava.