'The tomb was found in a buried ridge' It is commendable how researchers do not give up digging, quite literally. I also understand this is intensely a resourc

'The tomb was found in a buried ridge' It is commendable how researchers do not give up digging, quite literally. I also understand this is intensely a resource (time and money) consuming process. However I wonder why and how this was not discovered until now. Can't we disperse autonomous devices/robots that discover hollow spaces deep underground using SONAR or other vibration techniques?