How do I mine safely in the underworld without Ash falling on me?

While mining in the underworld I noticed that ash block behave in a very peculiar way, like a hybrid of sand and solid blocks. They can stay up without needing support by blocks below them, but if you mine in the vicinity they sometimes fall down.

I've had a whole section of ash collapse on top of me, which is annoying, it hurts and after cleaning up the resulting cave is large enough for imps to spawn inside. I also had parts of my tunnel collapse when trying to fill emtpy space with blocks to prevent imps from spawning.

• How do Ash physics work? When do the blocks fall?
• What are effective mining strategies to prevent lots of ash collapsing into my tunnel?

Solution 1:

From the 1.0.5 change log

Mud and ash now have a chance to fall like sand when struck.

Playing with it currently I seem to get a mud slide about 1 in 4 mud blocks dug, as the chance is presumably calculated for all neighbouring blocks the actual chance per block is likely lower

As for mining, make a ceiling out of stone or dirt and dig under it, digging down should be easy, be careful when digging sideways to dig at your farthest reach.

for mud you can also plant jungle/mushrooms in it which seems to prevent the falling chance, this would be quite situational as normally if you are tunnelling through it you will be removing the grass/fungi too

EDIT

from the 1.0.6 changelog

Ash and Mud no longer fall due to gravity.

so ash/mud physics is now of interest only as an historic note (unless it comes back again)

Solution 2:

According to Terraria_Blue, one of the devs for Terraria:

As of 1.06, Ash and Mud no longer has a chance to fall due to gravity when placed or dug.

http://twitter.com/#!/Terraria_Blue/status/100638502127022080

Solution 3:

Reedit: The likely point of the introduction of physics to Ash was to make it impossible to guard oneself from being attacked in the underworld: Hellstone is obvious, plentiful, and well-guarded. For game balance, the well-guarded aspect is, as you might be able to surmise, pretty damned important (no pun intended).

Whenever a block is placed or removed next to an unsupported mud/ash block; it has an approximate 1 in 4 chance of taking note of this change and falling to the ground. Of particular interest is the fact that this slide can trigger any blocks next to the now falling block to fall in turn; and any blocks near the landing site as well.

Wether it falls or not is random; it is not determined by the number of chained unsupported blocks.

The best way I've found to mine Hellstone is to carry a Staff of Regrowth or better on my person at all times, as well as an Obsidian skull to negate the damage from the Hellstone itself, and always burrow in from underneath the top of the deposits, leaving the top block of every column.

The size and commonness of the deposits more than justifies the "waste" that is the top block of every column, as you can get to the next deposit faster and with less tricky maneuvering.

Edit: My point, basically, is that the physics change to Ash and Mud pretty much negates the old guide to digging out Hellstone, making it a whole lot more difficult.

Then again, Hell is supposed to suck (c.f. The Nether, Hidden Fun Stuff)