t0 (shock ? @spock) t1 (internal pressure & then ) blurp (volume/pressure ratio %%) @ closest surface weakness and/or thickness t2 surface spreading + side corrosive (more or less) underground(/?/residual) spreading t3 whirlpool in//out more or less around other big shock center ( / materials compression center // border %weakness aftershock at first related) t4 ? hum hum hum !?! ("could" also tend to mean that sputnik planum is an older shock)