I understand that somatic mutations occur during the development of cell and are not transferred from one generation to other.

I analyzed a whole genome seq data It showed me that there are 30 variations which are specifically somatics in matched tumor vs normal . Of these, 30 only 1 is in exonic region rest are in either promoter, intron, UTR regions. I could not find out how somatic mutations are identified in non exoinc regions. In such case are non exonic mutations with somatic status may be equally valuable or not.