Arabian Journal of Geosciences

, Volume 5, Issue 4, pp 599–606 | Cite as

Focal mechanism of Badr earthquake, Saudia Arabia of August 27, 2009

  • Khalid S. Aldamegh
  • Hesham Hussein Moussa
  • S. Nasser Al-Arifi
  • Sayed S. R. Moustafa
  • Moustafa Hemeda Moustafa
Original Paper


Focal mechanism solution of the 27th August 2009 earthquake (mb = 4.0) that occurred in the Badr area, northwest of Saudi Arabia, approximately 50 km from the Red Sea has been determined from the P-wave first motion polarities. Results show normal faulting mechanism with a negligible component of strike-slip motion with NE T-axis direction. This type of mechanism is common with other earthquakes of the northwestern Saudi Arabia and is considered to present the tectonic movement of the region. The dominantly extensional tectonic regime in this province demonstrates the influence of NE extension in the Red Sea. The strikes of the solution are consistent with those of the main faults near the epicenter. Hypocentral location of this earthquake was carried out using the data from the King Abdulaziz City of Science and Technology Seismic Network, Saudi Arabia, and the Egyptian National Seismological Network, Egypt. The horizontal and vertical confidence estimates are 0.5 km for both. The local magnitude, M L, following the Richter’s original definition was also derived from ten digital three-component broadband seismograms. The average local magnitude determined in this study is 3.8 ± 0.17. The estimated seismic moment of this event is \( {3}.{\hbox{7e}} + {14}\,{\hbox{Nm}}\left( {{M_{\rm{W}}} = {3}.{66}\pm 0.0{7}} \right) \).


Focal mechanism Badr earthquake Moment magnitude Seismotectonics 

دراسة ميكانيكية البؤرة لزلزال 27 أغسطس 2009 بمنطقة بدر بالمملكة العربية السعودية

الملخص العربى

تم تحديد ميكانيكة البؤرة لزلزال 27 أغسطس 2009 الذى وقع في منطقة بدر ، الى الشمال الغربي من المملكة العربية السعودية ، حوالي 50 كيلومترا من البحر الأحمر والذى بلغت قوته المحسوبة من الموجات الأولية ٤ وذلك بإستخدام اتجاه الحركة في بداية وصول الموجات الزلزالية الأولية.وتشير النتائج إلى حدوث فالق عادى بالإضافة إلى مركبة ضئيلة من الحركة الإزاحية يأخذ نفس إتجاه الفوالق الرئيسية القريبة من البؤرة الزلزالية وبمحور شد يأخذ إتجاه شمال شرق. وتتفق هذه الميكانيكية مع الميكانيكية العامة لزلازل شمال غرب المملكة العربية السعودية. كما يتفق الإتجاه السائد لمحور الشد مع اتجاه حركة الإنفراج في البحر الأحمر. وقد تم تحديد موقع هذا الزلزال باستخدام بيانات الشبكة الزلزالية لمدينة الملك عبدالعزيز للعلوم والتقنية بالمملكة العربية السعودية و الشبكة المصرية الوطنية لرصد الزلازل بمصربدقة تصل الى نصف كيلو متر لكل من المسافة الافقية والعمق.وقد تم ايضا حساب القدرالزلزالى من عشر تسجيلات زلزالية رقمية واسعة النطاق ذات المركبات الثلاثه باستخدام التعريف الاصلى لريختر. وقد بلغت متوسط القدرة المحلية المحددة في هذه الدراسة 3.8 ± 0.17. و يقدر العزم الزلزالى المحسوب لهذا الحدث بحوالى 3.7 1410x نيوتن متر وهو مايساوى قدرا زلزاليا 3.66 ± 0.07.


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Copyright information

© Saudi Society for Geosciences 2010

Authors and Affiliations

  • Khalid S. Aldamegh
    • 1
  • Hesham Hussein Moussa
    • 2
    • 3
    • 4
  • S. Nasser Al-Arifi
    • 3
    • 5
  • Sayed S. R. Moustafa
    • 2
    • 3
  • Moustafa Hemeda Moustafa
    • 1
  1. 1.Astronomy and Geophysics Research InstituteKing Abdulaziz City for Science and Technology (KACST)RiyadhSaudi Arabia
  2. 2.Seismology DepartmentNational Research Institute of Astronomy and GeophysicsHelwanEgypt
  3. 3.Community CollegeShaqra UniversityAlquwayiyahSaudi Arabia
  4. 4.North Africa Seismological Group NASG Net40/OEA/ICTPTriesteItaly
  5. 5.Geology Department, Faculty of ScienceKing Saud UniversityRiyadSaudi Arabia

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