I believe everybody in Turkey will ask for TOKI :LOL:, if you asked for toki 1 month ago they would laugh at you. Kudos to TOKI, i remember people of forums made fun of TOKI.
Morrocan approach is most smartest under the Arab world, you are building aerospace industry with building little things. Other Arab countries are paying billions to do what you are going to do with no ToT:LOL:.
That side of Turkey soil is not solid rock, you are correct because of that houses sunked in the ground. Againg this is a common building technic and it is not easy to do it in solid rock, so how do you want to put a hole of 20 meters?