building a spatial database for earthquake risk assessment and...

Building a Spatial Database for Earthquake Risk

Assessment and Management in the Caribbean

Jacob Opadeyi and Rehanna Jadoo

Department of Geomatics Engineering and Land Management,

The University of the West Indies , St. Augustine,

Trinidad, West Indies.

Email: [email protected]

mailto:[email protected]

•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

OUR VULNERABLE LAND MASS

Geomorphology and Land cover 2007

Roads and Building Density

Slope and Soils Erosion

THE CONSEQUENCES

Damage to Buildings in Haiti due to the Earthquake of 2010

Risk Management Framework

Description of intention Hazard

mapping

Vulnerability assessment

Estimation of magnitude of consequences

Estimation of probability of consequences

Risk estimation

Risk evaluation

Risk management

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.

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.)

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: e.g.

RISK ($$/YR) = SUM( HAZARD [YEAR-1] X ASSETS [$$] X FRAGILITY [0-1])

Uses of Earthquake Risk Assessment (C. Benson and J. Twigg, 2004)

•Predicting the expected impact of earthquakes

•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.

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


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


C. Vulnerability data

Proximity of assets to active and inactive fault lines

Age of structures

Population and development density

Value 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

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.

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

programmes

Earthquake risk policy and legislation

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: www.consrv.ca.gov/cgs/rghm/psha/Pages/index.aspx; Figure 3Source:

Seismic risk mapping in Germany, Tyagunov et al 2006

http://www.consrv.ca.gov/cgs/rghm/psha/Pages/index.aspx









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.

Peak Ground Acceleration Map Overlaid on landuse to show

areas subject to Heavy Shaking

Peak Ground Acceleration Map & Critical Facilities Subject to

Heavy Shaking

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.

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 Web-based

materials.

Feature Identity Database

The feature identity database is made up of variables that provide general information about the facility e.g. location, name, contact information, name of person in charge etc.

Many of these variables can be collected in the field using mobile GPS/GIS technology.

Fac_ID

P_KEY

Nfac_

Code

Fac_Type Name Address Locality Tel Fax

23 12 Health center

Chaguanas District Health

Facility

Corner Galt St. and Chaguanas

Main Rd. Chaguanas 665-8958

24 61 Police Station Chaguanas Police Station Railway Rd. Chaguanas 665-5271

25 41 Air Field / Runway

National Helicopter Services

Ltd. NHSL Heliport, Camden Couva 679-2628 679-2345

26 XX XXXXXXXXX XXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXX XXXXX XXXXXXX XXXXXX



Feature Amenities Database

The feature amenities database is made up of variables that provide information about the facility’s service amenities .

This data should be collected by the relevant agency (government / private) responsible for the facility.

Amen

_ID

Fac_ID

F_KEY

Floor_space Parking_sp Parking_

sz

Generator Water

_cap

Pump Toilets_

unisex10

23 2400 20 70 YES XXX YES XX

1124 XXXXXXXXXX XX XXXXXX YES XXX YES XX

1225 XXXXXXXXXX XX XXXXXX YES XXX YES XX

1326 XXXXXXXXXX XX XXXXXX



Feature Functions Database

The feature functions database is made up of variables that provide information about the facility’s

operations.

These variables will depend on the type of facility. For example, the variables for a medical facility will

include : Number of beds, Number of doctors, Number of nurses etc.

This data should be collected by the relevant agency (government / private) responsible for the facility.

Fac_ID P_KEY Health_

Beds

N_Doctors N_Nurses N_Ambulances N_Drivers T_staff

2360 XXX XXX XX XX XXXX




Structural Integrity Database

The structural integrity database is made up of variables that provide

information about the integrity of the facility’s construction design.

This data should be compiled by engineering, construction and inspection

experts, in coordination with the relevant agency (government / private)

responsible for the facility.

Examples of variables that should be included and assessed include

vulnerability of building foundation, columns, beams, supporting walls etc.

These variables can be further broken down into more detailed evaluations and

tests as deemed necessary by relevant experts.

This information can be used to asses the facility’s structural vulnerability to the

effects of earthquakes or other natural disasters.

Structural Integrity Database

Struc

_ID

Fac_ID

F_KEY

Found_v

uln

Column_

vuln

Supp_walls

_vuln

Beam

_vuln

Floor_slab

_vuln

yrs_safe

_usage

Damage

_history

Earthquake

Response

Possible

closure_reccom

100 23 XX XXX XXX XX XX XXXX




Compiling the National Built Assets Database

Chaguanas District Health CenterFAC_ID 23

Feature Amenities Database Feature Identity Database

Feature Functions Database Structural Integrity Database

Hyperlink images of facility and building plans. Front View

Side View

1st Floor

2nd

Floor

3rd Floor

Synchronization of Data with ArcGIS

Query & Analyse National Database of Built Assets

Many questions can be answered by querying and analysing this database, along with the

associated bio-physical characteristics of the land, providing decision-support for

policymakers:

How many built assets throughout the country require seismic retrofitting?

Which facilities have been designated as shelters in the event of a natural disaster?

Where are these shelters located?

What is the potential monetary loss/replacement cost should one/more of these built

assets collapse due to an earthquake?

Which facilities exist within the most hazardous zones?

In the event of an evacuation how many occupants will require special assistance?

Building Density in Anguilla

Building Density in Antigua

Building Density in Tortola

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.

A need for capacity development and enhancement

Review of relationship with related agencies

Lack of a database on building structures

Vulnerability assessment of communities

Obtaining political support

Thank you

building a spatial database for earthquake risk assessment and...

Documents