tsunami command

Paste in Inpulse
/summon ArmorStand ~-35 ~-0.5 ~ {Invisible:1,NoGravity:1}

Paste in Repeat, no conditional, and always active
/execute @e[type=ArmorStand] ~ ~ ~ /tp @e[type=ArmorStand] ~ ~ ~0.1

Paste in Chain, conditional, and always active
/execute @e[type=ArmorStand] ~ ~ ~ /fill ~20 ~10 ~ ~-20 ~10 ~ water
/execute @e[type=ArmorStand] ~ ~ ~ /fill ~20 ~10 ~-1 ~-20 ~1 ~-1 air