Can high voltage main transmission lines be buried?
Yes. Very pricey. Just a question of capital expenditure. Good time to add wire to reduce power losses, too.
The big transmission line in Broken Arrow (looks like about a 161 kv trunk to me, but not completely sure) went down for about 1/2 mile. Metal and wood poles. About 500 ft east of friends in Broken Arrow - we were visiting during that storm and it was a wild ride. The house across the street, and several others around there, from them lost a tree, and power was out for about 8 hours - they were lucky! That tornado didn't quite make it all the way to the ground, otherwise, there would have been some serious issues. As it was, lots of houses damaged, but no one seriously hurt! Could easily have been a Moore type event - the damage path as it happened was hundreds of feet wide through those neighborhoods from Aspen to Elm!