It can rapidly form in 500 years with a smaller layer, but normally formation takes 20-30 million years.
Some people could drown in tsunamis other people could get stuck in the waves and crash into hard objects.
I hope that this helps you :-)
Tectonic plate movement is run by convection of mantle currents.
The Sun's increase in activity.
option 2 most major cities begin next to bodies of water
