THE SCIENCE: ELECTROMAGNETIC AND MAGNETIC AIRBORNE SURVEYING Electromagnetic (EM) / resistivity surveying is used to rapidly map the electrical properties of the subsurface, allowing information to be obtained about underground water (hydrology), soils and rocks. Resistivity measures how easily (or not) electrical current passes through a material. Fresh rock is generally a poor conductor of electricity so has a high resistivity. Metallic materials and water are good conductors and therefore have low resistivity. The purpose of magnetic surveying is to identify and describe regions of the earth’s crust that have unusual magnetic signatures. Glass Earth uses magnetic surveys to help with locating different rock types and structures such as faults and fractures. These different surveys help us to determine the possible location of mineral deposits. Airborne EM and magnetics surveys have very little environmental impact, allow the coverage of a large region, and are particularly useful for the areas where ground access is difficult. The surveys can be conducted using either a fixed wing aircraft, or, in the case of the Otago survey, a helicopter to provide greater operational flexibility and better lateral resolution. For more information on the science behind the survey please see the information page.

The South Island Otago geophysical survey is part of a second major Intervention Project carried out by Glass Earth in New Zealand, the first being the Coromandel / Central Volcanic Region Intervention Project in the North Island undertaken in 2005.