Re: The role of water in plate tectonics (is water necessary for plate

Groundwater can be an important factor in faulting and earthmovements such 
as for earthquakes caused by faulting.   I'm not sure, but doubt that 
water is necessary for plate tectonics to take place.   This activity is 
on a continental scale and very deep seated.   At great depths and very 
high temperatures molten rock may become a more important lubricant than 
water.   At those depths water probably doesn't exist in the liquid form.  
I suggest that you pursue a more in depth answer by searching sites on the 
internet.