This document summarizes magnetotelluric (MT) data collection and analysis to explore geothermal potential in the Rahat volcanic field in Saudi Arabia. 65 MT sites were surveyed across a 1050 km2 area with 5 km spacing. Data was analyzed using 2D and 3D inversion models. Results identified two resistivity peaks in the northwest and southern ends, possibly indicating geothermal reservoirs. The study recommends additional close-spaced MT soundings and expanding the survey area to better define deep resistivity structures.

1. Geothermal exploration using
magnetotelluric data, Rahat volcanic field,
Madinah city, Saudi Arabia
Essam Aboud 1, Faisal Alqahtani 1,2
eaboudishish@kau.edu.sa
1 Geohazards Research Centre, King Abdulaziz University, Jeddah, Saudi Arabia.
2 Faculty of Earth Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
P.O. Box: 80206
Jeddah – 21589
Kingdom of Saudi Arabia
Fax: +966 12 629 1894
Website: http://www.ghrc.kau.edu.sa
Email: ghrc@kau.edu.sa
Locate Us: 21.500470°N, 39.249318°E
Geohazards Research Center
‫اجليولوجية‬ ‫املخاطر‬ ‫أحباث‬ ‫كز‬‫مر‬
| Geohazards Research Center | King Abdulaziz University | ghrc@kau.edu.sa
03 - 05 March 2020 / Jeddah, Kingdom of Saudi Arabia

2. • Introduction
• MT method
• Data acquisition
• Data analysis
• Results and Interpretation
• Conclusions
• Recommendations
Outlines

3. The Arab Conference on Astronomy and Geophysics 5th Assembly 17-20 Oct. 2016

5. - The two curves are identical over 1D medium
- Different over 2D and 3D medium (in the presence of noise)
(W. Cumming, 2007)

6. MT site
Hx
Hy
Ex
Ey
Hz
North Harrat Rahat MT
- Dipole lengths - 50 to 70 m, oriented to magnetic North
- All sensor buried (20 – 50 cm) – minimize wind noise
 65 MT sites surveyed
 ~ 5 km spacing
 1050 km2
 Recording period (20 – 25 hours)
 Some stations were 48 hours

8. 2D maps

9. 2D maps

10. More depths

11. - Horizontal grid - 18 x 19 km
- Horizontal size = 2 km
- Horizontal distances = 80 km
- Maximum depth = 80km
- Homogeneous half-space
resistivity = 1000 ohm
-WSINV3DM
 Final misfit (rms) between data and model = 1.26
 Depth is from the lowest surface (600 masl)

12.  Moderate and high resistivity removed from the 3D volume
 2 “peaks” NW and southern end of the survey area.
Ohm-m

13. Close spaced MT soundings
 Around the Historic eruption
 South of Matan volcano
 Define geometry of the deep low
 resistivity structures
Expansion of survey area
 North, West and North-west of
 current survey area
 Have better understanding of
 other regional and structures
Matan
Recommendations

14. VORiSA team