1. LOGO EM-38 INCA 2008 International Course on ArchaeoGeophysics 20 July-5 August 2008 in İznik, Turkey Ertan Pekşen

2. Company Logo www.themegallery.com Outline IntroductionConclusion EM-38 Data acquisitionEquipmentInterpretationTheoryCase Study

3. Company Logo www.themegallery.com Introduction  EM38 has been produced by Geonics. (www.geonics.com)  EM38 is mainly used in agriculture, environmental, archaeology.  EM38 is easy to apply and carry during data acquisitions. EM-38

4. Company Logo www.themegallery.com Equipment EM-38

5. Company Logo www.themegallery.com Theory  Described by McNeil (1980)  Step 1: An alternating current in the transmitting coil creates a time-varying magnetic field which is sensed by the receiving coil.  Step2: This primary magnetic field (Hp) generates small electric currents in the soil.  Step3: These currents generate a secondary magnetic field (Hs) which is also measured by the receiving coil.  Step 4: The apparent conductivity may be determined from the ratio of the magnetic fields by the relationship. EM-38

6. Company Logo www.themegallery.com Data acquisition 4 2 1 3

7. Company Logo www.themegallery.com EM-38 specifications Frequency= 14.6 kHz T-R distance=1 m Horizontal and vertical dipoles EM-38 h=0.75m h= 1.5m Effective depth ranges Measured quantities: Measured quantities: 1)Apparent conductivities (mS/m) 2)In phase ratio of the secondary to primary magnetic field in parts per thousand (ppt)

8. Company Logo www.themegallery.com EM38 Apparent Conductivity  Fixed frequency: f=14.6 kHz  Fixed coil spacing: s=1 m  Apparent conductivity (B=s/  << 1): H p primary field H s secondary field  skin depth EM-38

9. Company Logo www.themegallery.com Interpretation EM-38 *Apparent conductivity map since the depth range is very shallow. depth range is very shallow. *Forward and Inverse modeling (Hilgendorf, 1997) and (Deidda et al., 2003)

10. Company Logo www.themegallery.com Case Study (Simpson et al 2008) EM-38

11. Company Logo www.themegallery.com …continued EM38 EM38DD provides simultaneous measurement of both (vertical and horizontal) dipoles at all times.

12. Company Logo www.themegallery.com Case Study EM-38

13. Company Logo www.themegallery.com Conclusion EM-38  EM38 can be applied to archealogy.  EM38 can quickly be carried out on a field.  EM38 provides information about underground no more than 1.5 m depth.

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