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C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

THE NIGERIAN NATIONAL NETWORK OF SEISMOLOGICAL STATIONS (NNNSS) BY OLOGUN, C.O., KADIRI, U. A. & YAKUBU, T.A. CENTRE FOR GEODESY AND GEODYNAMICS (CGG), NATIONAL SPACE RESEARCH AND DEVOLOPMENT AGENCY, FEDERAL MINISTRY OF SCIENCE AND TECHNOLOGY, TORO, BAUCHI STATE, NIGERIA A PAPER PRESENTED AT THE

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C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

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  1. THE NIGERIAN NATIONAL NETWORK OF SEISMOLOGICAL STATIONS(NNNSS)BYOLOGUN, C.O., KADIRI, U. A. & YAKUBU, T.A.CENTRE FOR GEODESY AND GEODYNAMICS (CGG),NATIONAL SPACE RESEARCH AND DEVOLOPMENT AGENCY,FEDERAL MINISTRY OF SCIENCE AND TECHNOLOGY,TORO, BAUCHI STATE, NIGERIA A PAPER PRESENTED AT THE IRIS workshop “Managing Waveform Data and Related Metadata from Seismic Networks” Helwan, Cairo, Egypt. 8TH – 17TH NOVEMBER 2009 • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  2. OUTLINE • GENERAL OVERVIEW OF THE GEOLOGY OF NIGERIA BASEMENT COMPLEX • 2. THE FRACTURE SYSTEMS IN NIGERIA AND ITS • RELATIONSHIP TO THE MID-ATLANTIC RIDGE 3. EARTH TREMOR OCCURRENCES IN NIGERIA 4. ACTION TAKEN SO FAR BY THE NIGERIAN GOVERNMENT - NTCEP • - NNNSS - CGG 5. INSTRUMENTATION/ANALYSIS SOFTWARE • 6. THE 9/11 EVENT • 7. CONCLUSION • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  3. GEOLOGY OF THE NIGERIA BASEMENT COMPLEX • Nigeria’s geologic terrain can be broadly divided into two: crystalline basement complex and the sedimentary basins. • The Precambrian basement complex is located within latitudes 7°N and 12°N and longitudes 3°E and 10°E. It forms a large part of the Pan- African mobile belt which lies between the West African Craton to the West and Congo Craton to the Southeast. • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  4. The region has been affected greatly by deformation • and/ or thermal reactivation during the Pan-African • event without extensive sedimentation. • Odeyemi (1981) classified the basement complex • rocks into three major groups, namely: • a suite of rocks comprising of migmatites • and gneiss; • (ii) metasedimentary successions (schist belts) which distinctly exist within the migmatites and gneisses; • (iii) a suite of intrusive syntectonic to late tectonic • granitoids (Older Granites) associated with • pegmatites and aplites. • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  5. Geologic map of Nigeria showing extension of Fracture zones from the Mid-Atlantic ridge to the Nigerian coastline (Whiteman, 1982) • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  6. EARTH TREMORS IN NIGERIA • Nigeria, like other parts of West Africa, lies on the • eastern flank of the Atlantic Ocean and unlike the • Pacific Ocean margins which are characterized by • subduction tectonics and occurrence of • devastating earthquakes, the Atlantic margins are • generally believed to be quiet and free of • diastrophic activities. • However, in recent times, earth tremors have been • reported in some parts of Nigeria. • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  7. Some towns where earth tremors have been reported are: • Lagos and Ile-Ife area in 1933 and 1939 • Warri area in 1933 • Ibadan, Ijebu-Ode, Akure and Shagamu on Saturday, • 28th July and Thursday, 2nd August 1984 • Yola in December, 1984 • Kombani Yaya on 18th June, 1985 • Ibadan on 27th June, 1990 • Okitipupa in 1997 • Akure and Ibadan in 2000 • Ese-odo & Okitipupa on 7th March, 2000 • Minna in April, 2006. • Recently in 11th November, 2009 (Recorded and processed) • Only 4 of these events were instrumentally recorded • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  8. ACTION TAKEN SO FAR BY THE NIGERIAN GOVERNMENT • SETTING UP OF THE NTCEP • ESTABLISHMENT OF NNNSS • ESTABLISHMENT OF CGG • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  9. LOCATION OF NIGERIAN SEISMOLOGICAL STATIONS • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  10. Map of Nigeria showing location of seismographic Station (■-- Functional Stations) • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  11. A Typical CGG Station • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  12. INSTRUMENTATION • Theequipment at each station consists of: • DR-4000 data acquisition system • EP-105 broadband seismometer or SP-400 • short period seismometer • Global Positioning System (GPS) • Power source (Solar electricity and battery) • These are products of Eentec Scientific Inc., • U.S.A. • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  13. DR-4000 Recorder EP-105 Sensor • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  14. DATA ANALYSIS SOFTWARE • The SEISAN Seismic analysis software is a complete set of programs for • analyzing earthquakes from analog and digital data. • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  15. PRELIMINARY RESULT OF 11TH SEPTEMBER 2009 EARTHQUAKE DATE OF OCCURRENCE: 11 SEPTEMBER, 2009 ORIGIN TIME: 04:10:18.6 FOCAL DEPTH: FIXED TO 10 KM LOCAL MAGNITUDE: 4.8 MOMENT MAGNITUDE: 4.0 EPICENTRAL DISTANCE: 129 KM WEST OF LAGOS RMS: 0.4 • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  16. LOCATION PARAMETERS STAT SP IPHASW HRMM SE AMPLIT PERI AIN TRES DIS IFE BZ EP 310 58.96 51 0.6910 276 IFE BZ ES 311 26.89 51 -0.3110 276 IFE BZ AML 311 32.04 17078.2 0.26 276 NSU BZ EP 311 34.81 51 -0.6310 573 NSU BZ ES 312 31.82 51 0.3210 573 NSU BZ AML 313 27.30 2450.3 0.49 573 KAD BZ EP 311 55.14 51 -0.0510 731 KAD BZ ES 313 5.64 51 -0.0310 731 KAD BZ AML 313 45.44 1501.8 0.35 731 KEY STAT: Station AMPLIT: Amplitude SP: Instrument type, Component PERI: Period IPHASW: Phase ID AIN: Angle of incidence HR: Hour TRES: Travel time residual MM: Minute DIS: Epicentral distance SE: Second • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  17. C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  18. CONCLUSION • Nigeria is not located within the major • seismic belt of the world • Minor earthquakes and/or earth tremors had • occurred in different parts of the country. • Presently, 4 stations are functional. • Efforts are being made to install equipment • in 7 additional stations and network all the • stations for effective data acquisition and • proper monitoring of seismic activities in the • country. • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

  19. THANK YOU • C CENTRE FOR GEODESY AND GEODYNAMICS, NASRDA , TORO, BAUCHI STATE

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