International EM induction workshops
IAGA (International Association of Geomagnetism and Aeronomy) is one of eight associations within IUGG (International Union of Geodesy and Geophysics) and IUGG is one of thirty unions within ICSU (International Council for Science).
The main activity of IAGA working group I.2 is the biennial Electromagnetic Induction in the Earth Workshops, initiated in 1972. The 22nd EM Induction Workshop in 2014 is organized by the German EM community.
In the past, the workshops have been attended by over 300 scientists, covering all fields of EM related research. The workshop as a whole is suitable for graduate students and junior scientists. The international Electromagnetic (EM) Induction Workshops are the premier events for researchers around the world to exchange on latest developments in the field of geophysical electromagnetism.
The workshop starts with an icebreaker on 24 August and ends on 30 August with the conference dinner.
For more information please visit organizer’s website http://www.emiw2014.de.
Advanced Geophysical Operations and Services Inc. (AGCOS) in collaboration with National Mineral Resource University (SPMI), St. Petersburg, Russia, presented “Multifunction electroprospecting instruments for complex investigations, mapping, monitoring and exploration in a wide depth interval”, “Multifunction seabed EM receivers for coastal shelf and transition zones exploration” and “Application of magnetovariational profiling method (MVP) for geological mapping and mining exploration” at the 22nd EM Induction Workshop, Weimar, Germany, August 22 – 30, 2014.
Multifunction electroprospecting instruments for complex investigations, mapping, monitoring and exploration in a wide depth interval
Summary
The preference given to multifunction geophysical EM equipment in recent years is due to two things. On the one hand, the new technical features of modern instruments such as accuracy, wide frequency and dynamic band, similar software design for realization of different methods, intuitive operation, low weight, and portability. On the other hand, the economic considerations such as low cost, reduced net cargo shipping weight, smaller field crew size, required training time, etc. Another recent tendency is to add as many functions as it is economically feasible to multifunction equipment. The multifunction EM receiver GEPARD is largely in line with these tendencies. It has a wide frequency band (50,000-0.00005Hz), high sensitivity, wide signal band (0.1µV-10V), low power consumption, low weight, intuitive operation via touch screen user interface and several data transfer modes. GEPARD has a flexible configuration of channels (4 or 8), where any of the channels could be either electrical or magnetic and each channel has good EM noise protection and a combination of switchable, precise digital and analog filters. GEPARDs come equipped with induction coil magnetic sensors and low-noise non-polarizing electrodes, as well as a portable multifunction current source AT-100 with the corresponding frequency band.
Multifunction seabed EM receivers for coastal shelf and transition zones exploration
Summary
Multifunction seabed EM receivers for electroprospecting field surveys in transition zones (SMMT) and coastal shelf (AUSS) are intended for the use of land-based multifunction EM receivers GEPARD and induction coil magnetic sensors AMS-37. However, it is also possible to use other 2-ch and/or 5-ch geophysical EM receivers that meet the technical specification of the 5th generation instruments. Due to their low weight and physical dimensions, marine EM receivers could be deployed from relatively small vessels. Custom designed retrieval subsystems guarantee the recovery of the instruments and its environmental compliance with the maritime regulations. SMMT and AUSS marine EM receivers could be successfully used for both saltwater and fresh water environments. Special precautions have been taken into account during the design to reduce the noise effects of underwater currents and surface waves.
Application of magnetovariational profiling method (MVP) for geological mapping and mining exploration
Summary
In recent years the 5-component audiomagnetotellurics method (AMT) became very popular for mining exploration and geological mapping. This method actually combines two electroprospecting methods based on the use of the Earth’s natural electromagnetic (EM) field: audiomagnetotellurics (AMT) and magnetovariational profiling (MVP). The first method is highly sensitive to the behavior of the sub-horizontal layers, and the second – to subvertical boundaries or bodies. The MVP method, besides being a perfect complement to the AMT, can be used independently for mapping tectonic elements, as well as for exploration of conductive bodies with different shapes. The MVP method allows carrying out cost-effective, environmentally friendly, year-around surveys on any terrain since there is no grounding requirement, as well as the application of 3-component precision field tripods for the accurate and quick installation of induction magnetic sensors. Any 3- or 5- component fifth generation AMT/MT equipment be used for the application of the method in the field. However, the most cost effective would be 4 or 8 channel multifunction EM receivers Gepard with the MVP method incorporated in the design. The method of express estimation of conductive body parameters (shape, position, depth, inclination and conductivity) based on the MVP data provides unique opportunity to target drilling of the subsurface objects immediately during the MVP field survey.