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Is Sudan dangerous ?

Is Sudan dangerous ?. Jens Havskov Department of Earth Science, University of Bergen and Nada Ahmed, Geological Research Authority of Sudan, Khartoum. Global seismicity. Plate boundaries, earthquakes (yellow) and volcanoes (red). Earthquakes April, 2007. Last major earthquake in Africa.

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Is Sudan dangerous ?

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  1. Is Sudan dangerous ? Jens Havskov Department of Earth Science, University of Bergen and Nada Ahmed, Geological Research Authority of Sudan, Khartoum

  2. Global seismicity Plate boundaries, earthquakes (yellow) and volcanoes (red)

  3. Earthquakes April, 2007

  4. Last major earthquake in Africa

  5. Last significant earthquake in Sudan according to USGS

  6. East African Rift Map of East Africa showing some of the historically active volcanoes(red triangles) and the Afar Triangle (shaded, center) -- a triple junction where three plates are pulling away from one another: the Arabian Plate, and the two parts of the African Plate (the Nubian and the Somalian) splitting along the East African Rift Zone

  7. Africa epicenters

  8. Seismic hazard for Africa From USGS

  9. Sudan Seismic Network

  10. Geological Research Authority of Sudan

  11. Station techical information • Recording on MARS88 • Network consists of 3 stations • Sensores are 20 s Lennanrtz seismometers • Noise level resonably good Typical examples of noise spectra. Left is the vertical component from station JAWL and right the EW component of station SLAT. The Peterson (1993) noise model is shown: New High Noise Model (NHNM) and New Low Noise Model (NLNM).

  12. Operation • Total operational time about 50 % • Main problem is unreliable communication Monthly Number of Events through the period from Nov. 2003 to April 2007.

  13. JAWL station

  14. Field work

  15. Sudan eartquakes 1850-2007 Seismicity for Sudan prime area for the time period 1850 to April 2007. A total of 1021 events are shown. Magnitude symbols are proportional to size.

  16. Earthquakes recorded locally since 2003

  17. Global earthquakes recorded in Sudan Seismicity detected by SSN for the World and Sudan for the time period November 2003 to April 2006. A total of 185 events are available. Magnitudes are proportional to symbol size.

  18. An earthquake near Khartoum recorded by SSN

  19. Earthquakes near Khartoum since 1900

  20. Fault plane solutions

  21. Fault plane solutions near Khartoum Left: The 1993, M=5.5 event. Right: Composite fault plane solution using local data

  22. Central African Shear Zone

  23. East African-Antarctic Orogen (c. 650-500 Ma) Jacobs & Thomas 2004, Geology, 32: 721-24

  24. Magnetic map

  25. New Madrid Seismic Zone The Great New Madrid Earthquake of 1811-12 was actually a series of over 2000 shocks in five months, five of which were 8.0 or more in It was the largest burst of seismic energy east of the Rocky Mountains in the history of the U.S. and was several times larger than the San Francisco quake of 1905. New Madrid and Wabash Valley seismic zones with earthquakes larger than 2.5

  26. New Madrid vs Khartoum • Similar size of seismically active area • Interplate region • Similar current seismicity rate: A magnitude 5 or larger every 10 years, 2 magnitude 3 events every year • Well defined fault at New Madrid, not so at Khartoum area • No evidence of a large historical earthquakes near Khartoum

  27. What to do Local seismicity will be studied in more detail with portable seismographs, problem is very low seismicity Crustal structure unknown in Central Sudan, surface wave and recieverfunction studies in progress More detailed crustal structure needed to investigate possible large surface structures Conclusion: Some potential for dangerous earthquakes

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