Results of the controlled source radiomagnetotelluric (CSRMT) sounding method in the study of traps (dolerite sills) overlain kimberlite pipes are presented. Features of the morphology of dolerite sills are described. The pinching out of dolerite sills over pipes and the lowering of the roof of hosting rocks in the near-pipe areas can be considered as indirect signs of the presence of pipes. The CSRMT method can be used in the study of morphology of dolerite sills and mapping the roof of kimberlite hosting rocks.