Earthquake Safety in Trinidad and Tobago – A Call for Action!

1. Earthquake Safety in Trinidad and Tobago – A Call for Action! Richard Robertson, Lloyd Lynch, Joan Latchman, Walter Salazar, Stacey Edwards, Clevon Ash, Omari Graham, Cassandra La Barrie, Monique Johnson

2. Summary • Trinidad and Tobago is highly vulnerable to large earthquakes that will occur at close range as well as a major event occurring at a greater distance • Given the present building stock, existing building practises and regulation, the estimated human and economic loss from an extreme event could be significant – as many as 30,000 fatalities and more than US$5 Billion in damage in either of the two largest cities in Trinidad • The best way forward is to implement and sustain a national earthquake risk reduction program aimed at improving earthquake safety to a specific target level

3. Objective • Gather a wide representation of individuals, organisations and stakeholders with involvement in earthquake safety, to thoroughly assess the existing status of earthquake preparedness and to define a way forward to ensue resilience to future damaging earthquakes

4. Why? • Location & geologic setting of Trinidad and Tobago => susceptible to earthquakes • Increased vulnerability and present understanding of regional seismo-tectonics => the earthquake threat is significant • Mitigation requires a comprehensive strategy

5. How? • SRC and ODPM partnered to host a national consultation entitled “Earhquake Safety in Trinidad and Tobago – A call for action!” • Date: Monday 5-6th July 2010 • Participants: > key stakeholders from government, academia, private sector, ngo gatherned for 2 days

6. Thematic areas • Case for Action – the Earthquake Hazard • Case for Action – the Earthquake Risk • Operational Framework – National Disaster Management Institutions • Call for Action – Developing Working Groups & Committees; best practises

7. Participants • Over 120 participants including researcher, practitioner or consumer

8. Format • Invited speakers to define state of the art with respect to • earthquake hazard and risk assessment; • issues related to building profession, planning and regulation; • activities related disaster preparedness and mitigation • Panel-led discussions after each presentation

9. The evidence • There is mounting seismotectonic evidence that one or more earthquakes of extremely destructive potential is looming on the horizon in the SE Caribbean

10. Located Earthquakes 1955 – 2010/05 • North Paria Peninsula (deeper earthquakes (50-200 km) - the most significant earthquake source • Gulf of Paria (shallow earthquakes) • Southwest of Tobago (shallow earthquakes) • Southeast of Trinidad (30-100 km)

11. Active Fault in Central Range Using GPS measurements Weber et al has shown that 65% (~13mm/yr) of present day motion between the Ca-SA plate boundaries in the SE Caribbean is accommodated on the Central Range/Warm Springs Fault

12. Log N = a + b M • Zone 11 • North of Paria Peninsula: • log N = 3.643 – 0.783 M • Recurrence interval* (T=1/N): • M=7.7: 243 years + 1766 = 2009 • last big earthquake • M = 8.3 : 718 years Size of the earthquakes *Recurrence interval: refers to the average time between earthquakes of a particular magnitude or larger in a given seismic source

13. The evidence • The ground motions produced by these earthquakes are likely to exceed those experienced during most earthquakes that have affected Trinidad and Tobago in the last 200 years and will rigorously test the stress threshold of the built environment

14. Antigua – Compaction at Port 1974/10/08 Mag.7.4. Antigua – Elephant foot buckling spillage into bund 1974/10/08 Mag.7.4. Damage From Ground Shaking Strong ground shaking from such an earthquake can continue for more than two minutes during which time it is unsafe to move around within buildings.

15. HAZARD MAP 475 YEARS RETURN PERIOD PEAK GROUND ACCELERATION HAZARD MAP 2475 YEARS RETURN PERIOD PEAK GROUND ACCELERATION Rock conditions Rock conditions Port of Spain Port of Spain (0.33g) (0.58g) San Fernando San Fernando (0.52g) (0.28g) Point Fortin Point Fortin (0.48g) (0.26g)

16. The evidence • ~ 70% of commercial structures inspected by the Design Engineering Branch of the Ministry of Works and Transport for approval have not met suitable code requirements for earthquake resistance. • Commercial and industrial zones on the west coast will experience anomalously high ground shaking during strong earthquakes. This increases the possibility of exposure to secondary hazards such as fire, liquefaction, ground settlement and subsidence surge.

17. The evidence • Current risk transfer portfolio in Trinidad and Tobago is grossly inadequate to cover losses from a large earthquake: • less than 25% of properties are insured; • CCRIF contributions will provide governments with short-term liquidity not recovery • The national disaster management agency was only recently (2005) restructured and given the mandate and resources to manage disaster using contemporary approaches • The population at large is oblivious to the prevailing state of affairs

18. The Way Forward - I • Implement and sustain a national earthquake risk reduction program aimed at improving earthquake safety to a specific target level • Establish a National Earthquake Stakeholder Organizatoin (NESO) with a Steering Committee to take the work forward

19. The Way Forward - II • The NESO should be a public-private partnership to which any individual or organisation desirous of working toward Earthquake Risk Reduction should be invited to participate. • Arrange a meeting with the Government comprising of key ministers to brief them of the outcome of the meeting and the recommendations made with respect to Earthquake Risk Reduction • Organise a series of workshops/meetings to discuss and undertake the following: • Establish work groups and define a work programme • Establish a Steering Committee for the NESO • Designate an operational base • Develop a business plan for the organisation

20. Summary • Trinidad and Tobago is highly vulnerable to large earthquakes that will occur at close range as well as a major event occurring at a greater distance • Given the present building stock, existing building practises and regulation, the estimated human and economic loss from an extreme event could be significant – as many as 30,000 fatalities and more than US$5 Billion in damage in either of the two largest cities in Trinidad • The best way forward is to implement and sustain a national earthquake risk reduction program aimed at improving earthquake safety to a specific target level

21. Thank You! Seismic Research Centre University of the West Indies Gordon Street St. Augustine Trinidad and Tobago Tel: +1 868 662 4659 Fax: +1 868 663 9293 Email: uwiseismic @ uwiseismic . com Web: www . uwiseismic . com