1. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA J Miguel Miranda CGUL / IDL

2. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA “Tsunamis, earthquakes, hurricanes, volcanoes and other natural disasters now pose a greater global threat than war and terrorism. Finding ways of reducing the impact of natural disasters is vital.” The European Commission supports the UN Disaster Reduction Conference in Kobe - IP/05/51- Brussels, 17 January 2005 Earthquakes with less then 30,000 victims

3. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Why the phocus on natural hazards suddenly developed ? 1946, Havai 1883, Krakatoa 1992, Ilha Flores 2004, Sumatra

4. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA In the Iberian geo-environment tsunamis are rare (but violent) phenomena. Historical (red stars) and instrumental (black dots) events.

5. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Plato wrote about the destruction of the legendary city - new evidence suggests he was writing about a devastating tsunami: "There occurred violent earthquakes and floods...the island of Atlantis disappeared in the depths of the sea." That was how Greek philosopher Plato described the destruction of the legendary city. "... nor could the martial tribes of the Lusitanians and Cantabrians escape; no more could the ocean, with its tide (the ebb-tide, ebb and flow), which yet was terrible to the ancient inhabitants; at least, until where the Pillars of Hercules extend..." (FLAVIO JOSEPHUS Memories, translated by Georgeos Díaz-Montexano, 2002) Even Atlantis is “located” here and there are large historical traditions.

6. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA The 1st November 1755 earthquake and tsunami started modern hazard studies.

7. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Monitoring and Warning versus Hazard and Risk assessments.

8. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA LANDSLIDES EARTHQUAKES Where do they come from?

9. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA > The maximum wave elevation (MWE);  The maximum run-up  The maximum run-in  The velocity and the flow depth What are the most important parameters ?

10. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA What are the relevant processes for tsunami impact ? SHALLOW WATER RUN UP ELASTIC DEFORMATION Okada EHS equations

11. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA If the source is known the propagation can be accurately computed

12. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA If the source is known the propagation can be accurately computed

13. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA  Determinist approach: the worst case (easy in the case of the stronger yet credible event). However,  we need for probability descriptions (can tsunamis risk be mitigated by intervention on the “building code” side?)  How rare are tsunamis? How can we characterize the occurrence model? How to compute tsunami hazard in SW Iberia?

14. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA EARTHQUAKES LANDSLIDES SEA SURF DISTURBANCE PROPAGATION COASTAL INTERACTION PEOPLE + CONSTRUCTION +... What are the main phenomena ? + TIDES Efficiency Model reliability

15. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Deterministic Tsunami Hazard Approach  The case of the stronger yet credible event for the UK (DEFRA study). Variability of hazard is only a function of local morpological conditions.

16. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA What can be learned from earthquake statistics? In case tsunami sources are far away from the risk areas run-up is mainly a function of local topography and if earthquakes are the main tsunami generation mechanism we can build a statistical model using a more common phenomenon (earthquakes). Gutenberg Richter relationship: Earthquakes with M>=5 Not all earthquakes generate tsunamis

17. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA What can be learned from earthquake statistics?

18. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Observations follow always a GR-like relationship?

19. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA What is the physical mechanism ?

20. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Probabilistic seismic hazard assessment? GENERATION ATTENUATION SITE EFFECTS

21. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Cornell’s approach is based on the assumption that the probability of excedance of an effect Y in a study area can be obtained by adding the effect of all possible seismogenic contributions Chosing as random variables the magnitude and hipocentral distance Assuming that earthquake generation follows an homogeneous Poisson process; If atenuation is given by; We have for a specific place: Probabilistic seismic hazard assessment?

22. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA The homogeneous source areas

23. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA What are the main results of PSHE ?

24. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Probability tsunami hazard evaluation (PTHE) In case tsunami wave heights can be predicted (as a consequence of seismic hazard or independently) than inundation and associated effects can be predicted by deterministic numerical simulation. Ex for Oregon in http://pubs.usgs.gov/ds/2006/236/figures/f_100-500cont.shtml

25. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA Can we forget the source ? Extreme value theory ?

26. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA PTHE must be meaningfull  DIscriminate between different levels of danger to people and goods;  Allow the design of mitigation strategies, including land management rules;  Allow the design of building codes;

27. NEW CHALLENGES CONCERNING GEO-HAZARD EVALUATION – J M MIRANDA THANKS !