Perspectives on Earthquake Risk Assessment and Management in Trinidad and Tobago

Transcription

1 Perspectives on Earthquake Risk Assessment and Management in Trinidad and Tobago Jacob Opadeyi Professor and Head Department of Geomatics Engineering and Land Management, The University of the West Indies, St. Augustine, Trinidad, West Indies. National Consultation on Earthquake Safety in Trinidad and Tobago July 5-6, 2010

2 Outline Review of Concepts Risk Assessment methods Data requirements Users and users of Earthquake risk assessment results Risk management activities Towards a Earthquake Risk Reduction Plan for T&T Prof. Jacob Opadeyi National Consultation on Earthquake Safety in Trinidad and Tobago July 5-6, 2010

3 OUR VULNERABLE LAND MASS Housing developments on drainage channels and steep slopes Unapproved development and land squatting Voluntary approach to the use of building codes Active seismic activities with geological faults Low level of awareness on the impact of natural hazards Low level of real estate insurance Prof. Jacob Opadeyi National Consultation on Earthquake Safety in Trinidad and Tobago July 5-6, 2010

4 Geomorphology and Land cover 2007

5 Roads and Building Density

6 Slope and Soils Erosion

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9 THE CONSEQUENCES

10 Damage to Buildings in Haiti due to the Earthquake of 2010

11 Risk Management Framework Risk managemen t Descriptio n of intention Hazard mapping Risk evaluation Vulnerabilit y assessment Risk estimation Estimation of probability of consequenc es Estimation of magnitude of consequenc es

12 EARTHQUAKE RISK ASSESSMENT What is Risk? Risks are an integral part of life and since risk cannot be completely eliminated, the only possible option is to assess and manage it. The first step in risk assessment is to find out what the problems are. This involves evaluating the significance of a given quantitative measure of risk in an integrated way.

13 EARTHQUAKE RISK ASSESSMENT Earthquake risk assessment encompasses the range of studies required to estimate the likelihood and potential consequences of a specific set of earthquakes of different magnitudes and intensities. Seismic scientists and engineers provide the key decision-makers with a description of the nature of the earthquake risk in specific regions as well as the degree of uncertainty surrounding such estimates. Quantitative estimates of seismic risk are important for judging whether earthquakes represent a substantial threat at any location as they enable objective weighting of earthquake risk relative to other natural hazards and other priorities for making design and retrofit decisions (NRC, 1996.)

14 Methods 4 major steps (Batuk et al 2005) 1. Hazard Analysis quantifies the physical characteristics of a hazard, including probability of occurrence, magnitude, intensity, location, influence of geological factors 2. Exposure Analysis identifies and maps underlying elements at risk or exposures, including the built environment and socioeconomic factors such as population and economic activity 3. Vulnerability Analysis: Assesses the degree of susceptibility to which elements at risk are exposed to the hazard. A common form of vulnerability analysis uses historical damage records to prescribe relationships between damage to dwellings and hazard intensity, for example different buildings and construction types will have distinct vulnerability curves, and finally 4. Risk analysis synthesizes the above three components and determines the resulting losses as a function of return period or as an exceedance probability

15 Uses of Earthquake Risk Assessment (C. Benson and J. Twigg, 2004) Predicting the expected impact of earthquake of projects Identification of appropriate risk management strategies Predicting the impact a project would have on forms and level of vulnerability in the wider community Help to formulate national policy objectives such as land use planning and building codes it provides cost efficient decision support on how to optimize investments into risk reducing measures in three situations, namely, prior, during and after an earthquake. Prof. Jacob Opadeyi National Consultation on Earthquake Safety in Trinidad and Tobago July 5-6, 2010

16 Data Required for Earthquake Risk Assessment A. Baseline data - Administrative boundary - Land cover, roads, streams etc. - Transportation and utility system - Facility and building structures - Demography (census, population distribution, density) - Economic value of asset of various sectors

17 Data Required for Earthquake Risk Assessment B. Hazard data Historical records (time, place, extent, magnitude / intensity) of earthquake hazard Geology, lithology, soil, and slope, water table Faults location, length, and depth Site condition, ground motion Existing method in hazard & risk assessment methodology

18 Data Required for Earthquake Risk Assessment C. Vulnerability data Proximity of assets to active and inactive fault lines Age of structures Population and demographic data Value and replacement cost of assets Location of critical facilities: Hospitals, Schools, Prisons, Banks, Public offices Construction materials used in buildings Location of lifelines: telecommunication, water, gas, power, transport systems

19 EARTHQUAKE RISK MANAGEMENT What is Risk Management? Risk management means reducing the threats to life, property and the environment posed by the hazard whilst simultaneously accepting unmanageable risks and maximizing any associated benefits (Smith, 1996.) Risk management involves the efforts of a variety of sectors and series of actions. In the case of earthquakes, risk management describes the role of seismic monitoring in developing alternative strategies for reducing future losses and aiding the recovery process.

20 Earthquake Risk Management Measures National risk reduction program Disaster preparedness and response plans Disaster recovery plans (National and sectoral) Earthquake hazard maps Earthquake early warning systems Landuse planning Building codes and development regulations Insurance schemes Development incentive programmes Efficient risk communication strategies Public education (use of simulators) Research and development

21 Example of Seismic Assessment Products Figure 1 Colour Coded Seismic Hazard Map pubs.usgs.gov/fs/2003/fs017-03/images/useqs.gif; Figure 2 Source: Figure 3Source: Seismic risk mapping in Germany, Tyagunov et al 2006

22 Case Study: Comprehensive Earthquake Risk Reduction Program and Action Plan: Marikina Task 1. Stakeholder User Needs Assessment: The first task will identify primary stakeholder concerns and interests. Using available GIS data and scenario modeling, it characterized stakeholder concerns in terms of known earthquake risk to valued community assets. Task 2. Data Inventory Comparison of existing GIS data resources with needs emerging from Task 1 Analyzes data collection and integration issues. Task 3. Risk Assessment Formalization of findings from a risk assessment regarding loss of housing, critical infrastructure, and economic development opportunities resulting from a 7.0 Magnitude earthquake.

23 Estimated Ground Shaking for Metro Manila in a 7.0 Magnitude Earthquake along the West Valley Fault

24 Existing and Planned Land Use Map of Metro Manila

25 Peak Ground Acceleration Map and Commercial & Industrial Areas Subject to Heavy Shaking

26 Peak Ground Acceleration Map & Critical Facilities Subject to Heavy Shaking

27 Comprehensive Earthquake Risk Reduction Program and Action Plan: Marikina Task 4. Prepare Conceptual Earthquake Risk Reduction Plan. This task created a conceptual framework based on a strategic planning process It assesses implementation options for the Comprehensive Earthquake Risk Reduction Program including locally feasible goals and objectives, policies/strategies and programs/projects for mitigation, preparedness, response, and recovery.

28 Comprehensive Earthquake Disaster Reduction Program and Action Plan: Marikina Critical Facilities Objective 1: Protect and strengthen infrastructure facilities to prevent loss of lives and damage to properties, to allow continued use, and to restore normalcy quickly following disasters. Policy 1.1: Report to the people concerned whether public and private buildings and infrastructure are in good condition Develop predisaster inventories of all utility lines to expedite post disaster identification of damaged facilities Study the replacement or upgrading of critical facilities particularly water lines. Program/Project Study the replacement or upgrading of power and telecommunication facilities. Project Establish a full coordination system with utility companies. Develop methods to ensure effective interprovider coordination systems to reasonable levels of service subsequent to a damaging earthquake

29 Critical Facilities Objective 1: Protect and strengthen infrastructure facilities to prevent loss of lives and damage to properties, to allow continued use, and to restore normalcy quickly following disasters. Policy1.2 : Preserve route functionality of roads and bridges for evacuation and logistics under all circumstances. Program/Project Study the vulnerability of existing roads and bridges and investigate possible improved locations in relation to land use Construct new major roads and bridges Retrofit infrastructure facilities which need to be strengthened.

30 Critical Facilities Objective 1: Protect and strengthen infrastructure facilities to prevent loss of lives and damage to properties, to allow continued use, and to quickly restore normalcy following disasters. Policy 1.3 : Construction of public and private facilities should take into account potential earthquake threats including liquefaction Identify earthquake hazardprone areas and areas safe for the location of public and private utilities and facilities Program/Project Modify the City Comprehensive Land Use Plan to reflect safe locations for public and private facilities Construct public and private facilities such as roads and bridges with adequate mitigation measures Require public and private facilities to address potential earthquake hazards.

31 Critical Facilities Objective 1:Protect and strengthen infrastructure facilities to prevent loss of lives and damage to properties, to allow continued use, and to restore normalcy quickly following disasters. Policy 1.4 : Restrict land uses downstream from the proposed road dike levees unless such facilities have been determined to incorporate adequate seismic stability. Program/Project Identify earthquake hazardprone areas and safe areas to locate road dike levees Develop a land use plan for the location of road dike levees Develop an evacuation plan in case of levee damage Others: New Buildings, Existing Buildings, Landuse planning, Public Education, Public Information, Research and Development, and Institutional Development

32 Comprehensive Earthquake Risk Reduction Program and Action Plan: Marikina Task 5. Plan Refinement and Implementation Strategy This task combined objectives, policies, strategies, programs and projects for mitigation, preparedness, response, and recovery actions into a Draft Comprehensive Earthquake Risk Reduction Program and Action Plan based on discussions held at stakeholders workshop. Task 6. Produce Final Products This task will include finalization of the Program and Action Plan along with Webbased materials.

33 What are the Challenges facing the Development of Earthquake Risk Assessment and Management in Trinidad & Tobago? Lack of a consistent data collection programme for risk assessment and management. Lack of an active public education programme. Capacity development and enhancement Review of relationship with related agencies Lack of a database on building structures Vulnerability assessment of communities Obtaining political support

34 Acknowledgement This presentation was prepared with support from the following graduate students: Candice Ramkisson, Gabrielle Thongs, Roxanne Smith, and Alicia Jackman

35 Thank you