The document discusses seismic hazard analysis for Saudi Arabia. It provides information on earthquake catalogs and homework instructions to analyze the number of earthquakes in Saudi Arabia above certain magnitudes since 1973. It also discusses using moment tensors to infer the main tectonic process and introduces seismic zoning and magnitude-frequency modeling for the region.

1. Introduction to Seismology Seismic Hazard Analysis 1 (pp.455-460) Department of Earth Sciences KFUPM Ali Oncel [email_address] Introduction to Seismology-KFUPM

2. There are several online catalogs of earthquakes. In this exercise, you will need to access one of these. For earthquakes any place in the world, a good place to start is: http://wwwneic.cr.usgs.gov/neis/epic/epic.html A catalog of focal mechanisms (CMT Solutions) is at the Harvard seismology site: http://www.seismology.harvard.edu/ You will need to use an Excel spreadsheet to solve some of these problems. Homework on Earthquake Search due May, 3 How many earthquakes occurred for the Saudi Arabia and vicinity since 1973 with magnitude 6.0 or larger. with magnitude 5.0 or larger. with magnitude 4.0 or larger. 2. Present your data, giving the average number of earthquakes per year and establish Log N= a – b M . 3. By consulting the Harvard catalog of moment tensors, for the largest of the events in this region, infer the main tectonic process in this region. Explain the reasoning behind your response. Introduction to Seismology-KFUPM

3. Introduction to Seismology-KFUPM Oncel, 2006

4. Depth=0-20km Time Interval: 1973-2005 Log (N)= 8.06 – 1.12 M Frequency-Magnitude Model Mc=4.6 Introduction to Seismology-KFUPM Oncel, 2006

5. Zoning : Spatial mapping of the variations in seismicity or earthquake strong ground motion (and identification of similar zones) Parameters to map: Occurrence of damaging earthquakes (Mallett 1858) Number of felt earthquakes (e.g. Balloré 1896) I o Macrozoning on the regional scale Microzoning takes into account localised conditions e.g. rock and soil type Recall: Seismic Zonation Introduction to Seismology-KFUPM

6. Microzoning for Saudi Arabia Introduction to Seismology-KFUPM Al-Amri (2005)

7. Al-Amri (2005) Introduction to Seismology-KFUPM

8. Introduction to Seismology-KFUPM Oncel, 2006 after Al-Amri, 2005 What about the M max ?

9. Magnitude prediction equations • Best known: Wells and Coppersmith (1994). – Distributed to the class. – Recommendation: read the article, and learn how to use these relations. Introduction to Seismology-KFUPM See pp. 437 of Bullen and Bolt

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12. Adams, 2006 Macro-/Microzoning for Saudi Arabia Introduction to Seismology-KFUPM Al-Amri, 2005

13. Abdalla and Al- Homoud (2004 ) Al-Amri (2005) Compared Models of Seismic Hazard Introduction to Seismology-KFUPM

14. Introduction to Seismology-KFUPM

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16. Abdalla and Al- Homoud (2004) Case Work: Eastern Arabia Introduction to Seismology-KFUPM

17. Seismic Zones on Eastern Arabia Introduction to Seismology-KFUPM Abdalla and Al- Homoud (2004)

18. Seismic Sources for Eastern Arabia Introduction to Seismology-KFUPM Abdalla and Al- Homoud (2004)

19. Maximum Expected Earthquakes for Seismic Sources Introduction to Seismology-KFUPM Abdalla and Al- Homoud (2004)

20. Hazard Parameters for Seismic Sources of Eastern Arabia Could you write Magnitude-Frequency Relations for Regions 1 and 2? Log N= 10.17 – 1.22 M Region 1 Log N= 6.99 - 0.94 M Region 2 What is the number of M7 for regions 1 and 2? Introduction to Seismology-KFUPM Abdalla and Al- Homoud (2004) 1008-2002

21. What is the Frequency? Log (N/T obs )= 10.17 – 1.22 M Region 1 Log (N/T obs )= 6.99 - 0.94 M Region 2 T obs = 995 years What is the number of M7 for regions 1 and 2? (N/T obs ) = 10 10.17-1.22* 7 (N/T obs )= 10 6.99-0.94* 7 0.043 for Region 1 0.03 for Region 2 Introduction to Seismology-KFUPM

22. What is the Recurrence Time? What is the recurrence period for M7 events? T(1)= 1/ (N/T obs )= T(2)=1/ (N/T obs )= 23.33 yrs 387.10 yrs Which of those regions has large hazard? Region 1? Or Region 2? Introduction to Seismology-KFUPM

23. Probability is given by formula as: P(t)= 1-e -t/T Recall T is recurrence time while t is years Then calculate the M=7 probability for 30 years? P(t)= 0.72 or % 72 for Region 1 P(t)= 0.07 or % 7 for Region 2 Introduction to Seismology-KFUPM What is the Earthquake Probability?