EARTHQUAKE MODELLING. Algiers, Belhassen Tonat

Transcription

1 EARTHQUAKE MODELLING Algiers, Belhassen Tonat

2 Basic terms Plate tectonics

3 Basic terms Average Number of Earthquakes/Year (Global) Magnitude Average Annually 8 and higher 1 ¹ ² ² ² from Engdahl and Villasenor, ,000 (estimated) 130,000 (estimated) 1,300,000 (estimated) ¹ Based on observations since ² Based on observations since from

4 Basic terms Magnitude L Aquila

5 Basic terms Intensity Subjective measure of the strength of an earthquake, assessed on the basis of local damage Discrete twelve-graded Mercalli scale Decreases with increasing focal distance Epicentre Km IX VIII VII VI

6 RISK How can we assess the Risk? hazard Risk vulnerability insured values

7 Hazard Earthquake catalogue f 10 Event frequency M Energy attenuation I = C 1 + C 2 M - C 3 log R f Intensity frequency Hazard map M M I

8 Hazard World map of natural Hazards: Earthquakes Earthquake Hazard Zones Zone 0 Zone 1 Zone 2 Zone 3 Zone 4

9 Hazard Seismic Hazard Map (with a return period of 475 years)

10 Hazard Seismic Hazard Map (with a return period of 475 years)

11 Hazard Seismic Hazard Map (with a return period of 475 years) L Aquila, 2009, Mw people killed Izmit, 1999, Mw people killed Boumerdes, 2003, Mw people killed

12 Hazard Seismic Hazard Map (with a return period of 475 years) GSHAP Expected peak ground acceleration with 10% probability of exceedance in 50 years (from Grunthal et al., 1999). 1954, Mw , Mw , Mw 6.8 (from Benouar, 2004)

13 Hazard Seismic Hazard of the Algeria The seismic hazard is not well known The historical seismicity in Algeria is imperfectly known: its coverage is discontinuous and its record is grossly deficient Return periods of the events and maximum magnitudes for the local sources can be difficult to assess The seismicity of the twentieth century is relatively well documented During the last thirty years several significant events already occurred (i.e.: 21 st May 2003, Algiers, Mw 6.8; 1980, El Asnam, Mw 7.3)

14 Hazard Microzonation and secondary effects Niigata (Japan) 1964 Liquefaction Mw 7.5, 1964 Niigata, Japan

15 Vulnerability Construction Type Masonry Steel Reinforced Concrete Chile, Mw /02/ Int (MMS) Destruction[%] Res_B Com_B Ind_B

16 RISK How can we assess the Risk? hazard Risk vulnerability Destruction[%] Res_B Com_B Ind_B Int (MMS) insured values

17 Modeling Earthquake Risk Hazard Data (MMI) Vulnerability (Loss Data) Exposure (Aggregate Data) PML curve PML (in %) Return period (years)

18 Loss assessment: example Hazard Data (Modified Mercalli Intensity) Vulnerability (Loss Data) Exposure (Aggregate Data) Events Date Loss data Exposure data PML in % El-Asnam 9. September 1954 X El-Asnam 10. Oktober 1980 *? Y Boumerdes 21. May 2003 * * Z

19 Loss assessment: example Hazard Data (MMI) Vulnerability (Loss Data) Exposure (Aggregate Data) PML curve PML (in %) X Y Z Return period (years)

20 THANK YOU FOR YOUR ATTENTION Algiers, Belhassen Tonat