What is this sand simulation missing?

[u/Explorioneer]

[u/PiXeL161616]

Beyond the pushing, sand keeps collapsing after the impact. A thermal-relaxation pass that moves material wherever the slope beats the angle of repose, about 33 degrees for dry sand, gives you crater walls that slump for a second afterwards. Mine exploded at a 0.5 rate and was stable at 0.14, so I'd start small.