Planetary magnetism

The electrical resistivity structure of the crust beneath the northern main Ethiopian rift

Magnetotelluric surveys measure the variations of the natural electromagnetic field on the Earth's surface. The induced part of the electromagnetic field provides information on the distribution of the electrical resistivity to a depth of a few kilometres. The method is passive and capable of revealing previously hidden structures that are invisible to traditional seismic techniques. MT surveys have successfully been used to image beneath basalt deposits on the Isle of Skye and Lake Tana in Ethiopia.

The Tana basin is covered with extensive Eocene-Oligocene continental flood basalts which mask underlying formations. The MT survey confirmed the existence of a Mesozoic sedimentary basin between lava flows and the Precambrian basement. The MT data assists exploration companies target activity more precisely at potential hydro carbon deposits, minimising risk and significantly reducing project costs.


Prof Kathy Whaler