Tsunami Hazard level: Medium
In the area you have selected (Maldives) tsunami hazard is classified as medium according to the information that is currently available. This means that there is more than a 10% chance of a potentially-damaging tsunami occurring in the next 50 years. Based on this information, the impact of tsunami should be considered in different phases of the project for any activities located near the coast. Project planning decisions, project design, and construction methods should take into account the level tsunami hazard. Further detailed information should be obtained to adequately account for the level of hazard.
Climate change impact: The areas at risk of tsunami will increase as global mean sea level rises. According to the IPCC (2013), global mean sea level rise depends on a variety of factors, and estimates for 2100 range from ~20 cm to nearly 1 m. However, regional changes in sea level are difficult to predict. Projects in low-lying coastal areas such as deltas, or in island states should be designed to be robust to projected increases in global sea level.
Recommendations
- TECHNICAL EXPERTISE: Engage qualified local or international experts, with experience in the local area, to determine the tsunami risk to your project. Request their assistance in design, implementation and maintenance planning to minimise tsunami threat. More information
CONTEXT:
- A tsunami hazard assessment should be carried out to identify what impacts may affect your site.
- This should include magnitude and frequency of tsunami.
- Consider whether local site conditions (nearshore bathymetry and topography) could amplify tsunami hazard. If the tsunami hazard is high enough in this area to warrant site-specific risk analysis.
- Other projects may have already dealt with tsunami hazard at this, or in a similar location or social context.
- Prior experience in the area may act as a starting point of project initiation, providing existing knowledge that can prove cost-effective. Lessons can be learned and effort saved by not re-inventing the wheel.
MITIGATION:
- Engage a qualified local or international tsunami expert with the goals of:
- Understanding the tsunami risk to the project
- Supervising design, construction, and maintenance from a tsunami risk mitigation perspective.
- Undertake evaluation of tsunami hazard and impact as part of project assessment.
- Find out if the exact project location is in a hazardous zone, e.g. by collecting local tsunami hazard information either from maps or by interviewing local governmental civil protection, indigenous communities’ members, and scientific organizations or international agencies if local knowledge/capacity does not exist.
- If the project is in a hazardous zone, collect more specific tsunami inundation data for the exact project location. This could start with performing tsunami inundation modeling for the range of possible tsunami threats to the project site.
- If the project site is within a tsunami inundation zone undertake a cost-benefit study of the risk of loss of the investment, or the benefit provided by the additional cost of engineered protection systems such as sea walls.
- Utilise traditional knowledge to increase understanding of tsunami risk in project area. Traditional and indigenous knowledge can contribute to understanding tsunami risk, especially when the written history of a tsunami is limited and geological evidence has not been investigated. Indigenous oral histories may contain inter-generational knowledge of events that have occurred prior to when written records began in the region.
- Utilise local knowledge to increase the resilience of project. Consider contacting local or international staff who have experience working in the project area to understand how they have sought to reduce tsunami risk. Previous or other current projects may have already considered the tsunami hazard assessment and risk management approaches required for this region, review their information.
- Collaborate with NGO, international organizations and others working in the area to share local knowledge.
Links:
International Tsunami Information Centre http://itic.ioc-unesco.org/index.php
Mainstreaming tsunami DRM https://www.gfdrr.org/two-years-after-tsunami-mainstreaming-disaster-risk-management
Designing for Tsunamis http://www.preventionweb.net/files/1505_DesigningforTsunamis.pdf
- REGULATIONS: Check with local authorities to identify any local regulations concerning tsunami hazard and impacts. Ensure that the project conforms to existing tsunami avoidance zone land use planning regulations, flood regulations and any existing plans for warning and evacuation. More information
CONTEXT:
- Around the world there is increasing recognition that avoiding development in the most frequently tsunami (or river flood or storm surge) inundated areas is one of the most effective means of managing future losses to natural hazards. Therefore, the planning for new developments should include consideration of already-existing national or regional regulations and guidelines
- Many countries have some form of formal legislation, regulation or guidance for tsunami risk mitigation. These may broadly cover such aspects as:
- Land-use planning, controlling the location of development for all or some types of building or project
- Warning, through natural signs (earthquake, ocean disturbance), local initiatives and/or Tsunami Warning Centres
- Response planning, usually focussed on life safety, evacuation routes, signage and safe locations
- Public alerting mechanisms such as mobile phone apps, sirens, radio etc.
- Hard defence options
- Vertical evacuation options
- Risk assessment
MITIGATION:
- Note that avoidance of a natural hazard such as tsunami is the most effective form of risk mitigation, but this should be a decision made based on the informed understanding of social, economic and political risk.
- Comply with laws and regulations including land-use planning and flood management. Design the project to best integrate the regulations.
- Comply with all Health and Safety obligations appropriate to the hazard level.
- If the location of the project conflicts with land-use planning regulations, or cannot comply with warning and evacuation regulations consider relocation of the project.
Links:
International Tsunami Information Centre http://itic.ioc-unesco.org/index.php
Pacific Tsunami Warning Centre: http://ptwc.weather.gov/
Indian Ocean Tsunami Warning and Mitigation System (ICG/IOTWMS), more information at: http://www.ioc-tsunami.org/index.php?option=com_content&view=article&id=8&Itemid=58&lang=en
North-Eastern Atlantic, Mediterranean and connected seas: Tsunami Information Centre. http://neamtic.ioc-unesco.org/
Examples:
NZ tsunami warning plan – http://www.civildefence.govt.nz/cdem-sector/cdem-framework/guidelines/national-tsunami-advisory-and-warning-plan/
NZ tsunami evacuation mapping guideline –< http://www.civildefence.govt.nz/assets/Uploads/publications/dgl-08-08-tsunami-evacuation-zones.pdf>
NZ public notification options assessments - http://www.civildefence.govt.nz/cdem-sector/cdem-framework/guidelines/public-alerting-options-assessment/
Integrating tsunami inundation modelling into land use planninghttp://www.eqc.govt.nz/sites/public_files/1604-tsunami-inundation-modelling-into-land-use-planning_0.pdf
- LOCAL IMPACT: Consider the effect that the destruction or serious damage to buildings and infrastructure associated with the planned project could have on the local population and environment. More information
CONTEXT:
- Debris resulting from tsunami impact often contributes to additional damage, so consider whether debris coming from the project could add to consequential damage to other structures and infrastructure for hundreds of meters to kilometers both along the coast and inland from the project location.
- Loose debris may comprise elements from the natural environment (including tree trunks, boulders, rocks and coral from on land or the seabed, and sand and silt), and the built environment (including log storage awaiting shipment, containers, parts of buildings and their contents such as furniture, pipes and wiring, and boats).
- Floatable buildings (primarily those that are timber-framed) can be damaging once caught in the tsunami surge.
- Both structural and non-structural building elements can potentially cause damage. Elements of note include metal cladding and roofing, panels, interior furniture, and fittings.
- Storage tanks are prone to rupture or floating away, resulting in spillage of contents. This is especially dangerous if the contents are toxic or flammable.
MITIGATION:
- Consider how loose debris from other sources could impact on the project and build to withstand potential debris strike as much as possible.
- Reinforced concrete tied to strong deep foundations are the most resistant structures to tsunami and its entrained debris
- Consider water flow, with potential entrained debris, coming from the sea-side of the project, along the shore, and from inland as the water recedes. Erosive scour and some of the major damage due to debris impact has been observed to occur during the outflow of tsunami flooding.
- If the consequences of tsunami damage are unacceptable consider moving the project.
- Build using reinforced concrete with deep strong foundations.
- Store materials loose and floatable materials above the estimated maximum potential tsunami inundation depth where possible to prevent them being entrained as debris.
- Minimize the volume of toxic or flammable materials (especially fluids) on site during construction and operation.
- Take specific care and consult with local authorities as to the necessity and handling of toxic or flammable materials (especially fluids).
- Consider developing warning and evacuation plans for the project.
- Make sure that on-site emergency services, such as generators, are located above the estimated maximum potential tsunami inundation depth.
LINKS:
Designing for Tsunamis http://www.preventionweb.net/files/1505_DesigningforTsunamis.pdf
- UTILITIES AND ACCESS: Consider the impact of tsunami inundation on the availability and function of: transport, communications, water, sanitation and energy infrastructure, and public health for continued operation of the project. More information
CONTEXT:
- A project may be situated far from the coast but still be sensitive to loss of services.
- Failure to function or lack of availability of these essential services may compromise the building of the project, the functionality, or the financial viability of the completed project.
- Public administration and services such as governance, banking and health may be disrupted due to either direct damage or diversion of resources.
- Transport routes are regularly disrupted in tsunami, due to the coastal location and orientation of roads, train lines, bridges and airports.
- Ports are regularly damaged by tsunami.
- Communications, communication cables and energy networks often follow the roads and may cross waterways on bridges that are vulnerable to tsunami impact.
- Energy supply, refining, and storage facilities are often in coastal locations. Near-shore and off-shore oil and gas supply platforms, bores and pipes are vulnerable. Shipping of energy (gas and oil tankers, etc.) relies on ports. Refineries often exploit low coastal plains. Power cables across oceans and small waterways may come ashore in areas at risk of tsunami.
- Fuel is often stored in coastal tank farms, which can be heavily damaged by tsunami. The tanks and fuel are often floating and possibly present as a direct hazard to the project. Tsunami and associated earthquakes can cause rupture of gas supplies and spillage of flammable materials. Fires may subsequently occur and spread on the water surface.
- Water and sanitation pipes and treatment plants are often in coastal areas and can be damaged by tsunami.
- Public health is often compromised following a tsunami due to damaged sanitation services, loss of refrigeration, water-borne disease and lack of availability of health services and food.
- Food distribution loss through transport, refrigeration, and storage, along with loss of supply from agricultural, fisheries and tourism impacts, is a common consequence of tsunami inundation.
MITIGATION:
- Consider which services are essential to maintain social and economic function of the project and the region during the months to years of post-event recovery. For these services:
- Discuss possible redundancy of services with the relevant infrastructure operators. For example, electricity and road networks that do not run parallel or close to the coastline.
- Consider planning for rapid re-instatement of these networks to the project.
- Consider on-site back-up supply of essential services. For example, backup power generation, and long term fuel supply availability. Independent wireless communication such as VHF radio could also be considered.
- Services may be made more resilient by incorporating higher engineering specifications designed for tsunami scour, lateral pressure, buoyancy, debris impact and fire.
- If the critical service dependencies are not able to be duplicated or hardened, then consider relocating the project to a location with more resilient services, even if the project location itself is not vulnerable to tsunami.
- CRITICAL INFRASTRUCTURE CONSIDERATIONS: If the project is involves the development of critical infrastructure (e.g., a hospital, fire station, or power transmission line), investigate the cascading effect of vulnerable network dependencies of the project (e.g. power supply and computer and communication networks) that may impact the project, even if the project itself is not inundated. More information
CONTEXT:
- For projects that are critical infrastructure (such as a hospital, a power station, or a key communications facility) there is a greater need and expectation that they will function post-event to maintain essential services or are a pivotal part of response and recovery efforts.
- Most projects rely upon incoming services such as electricity, water supply, workforce, etc., (‘upstream dependencies’) and provide services or products that are important to the local, regional or national economy and social wellbeing (‘downstream dependencies’). Thus, even when the project itself is damaged by the tsunami, it may not function.
- Thus, even if the project itself is not inundated or damaged by the tsunami it may not be able to fulfil its required role in the wider economy. If the project has supply guarantee deliverables, then the wider dependencies need to be robust to tsunami damage.
- Most common dependencies include energy supply (especially electric) and communications. These services are often supplied along the road corridor which runs parallel to the coast and is often supported by bridges. Coastal locations and bridges are highly vulnerable to tsunami, so it is likely these services will be damaged and unavailable following a tsunami.
MITIGATION:
- Consider which dependencies are vulnerable to tsunami. Consider backup or redundant systems where possible, in conjunction with service providers. For example, are there service corridors that do not run parallel to the coastline.
- Consider planning for rapid re-instatement of these services to the project.
- Consider on-site back-up supply. For example, backup power generation with long term fuel supply could be considered. Independent wireless communication, such as VHF radio may be vital at a time of crisis.
- If roads are in themselves important to the project, either for staff access or for post-event functionality (e.g. as an emergency service) consider alternative routing.
- If service failure cannot be avoided, consider relocation of the project.
- EARLY WARNING SYSTEMS: Early warning may be required to enable successful evacuation and to enable temporary shut-down of the project if this could reduce consequential and compounding damage. Consider the requirements for successful evacuation of the project location in case of a warning (e.g., adequate transportation, evacuation routes, and safe refuges by undertakeing evacuation planning and exercises. More information
CONTEXT:
- Some tsunami impacts can be mitigated through warning and evacuation.
- If people can be evacuated outside of the hazard zone it would greatly reduce the likelihood of death and injuries.
- If equipment and materials can be shut down, moved or secured, some impacts may be reduced. For example, the rapid evacuation of toxic or flammable materials, evacuation of ships, shutdown of nuclear power plants.
- The project must adhere to workforce health and safety regulations. Often, this places constraints on the design, construction, and operation of the project, and may require protocols to be developed to maintain staff safety during a tsunami. In cases of high hazard, there may be an obligation to develop or gain access to early warnings of impending tsunami arrival and to have evacuation plans in place to satisfy health and safety obligations.
MITIGATION:
- Early warning is possible for most tsunami, but be aware that substantial and sustained investment is needed for early warnings to be effective, timely and reliable.
- Regional warning agencies are noted in the Links section.
- Plans should be made including evacuation routes, safe locations and capacity/welfare/communication at those locations for evacuation in response to all warnings.
- Regular exercises are essential to test plans (at least annually, or more frequent to match staff turnover cycles) exercises are essential to test plans. Exercises also act as some of the most effective education, causing staff to rapidly learn the plan ahead of the exercise, and reinforce it with action.
- If shaking from an earthquake continues for longer than a minute or if people find it hard to stand up (not necessarily both) evacuate immediately. D and do not wait for any official warning – it is unlikely to come in time.
- For tsunami coming from further away, particularly the other side of the Pacific or Indian Oceans, there may be many hours of warning via the respective Tsunami Warning Systems.
- Both the Pacific Tsunami Warning Centre (PTWC) and Indian Ocean systems connect to formal government warning agencies, and the country’s government should be consulted for a link to receive warnings. The Pacific and Indian Ocean Tsunami Warning Systems are independent of one-another.
- As a fall-back, informal monitoring of the PTWC website can provide non-secure, non-guaranteed, delivery of warnings which may provide a basis for response.
- In areas where the travel time to high ground is prohibitive compared to the tsunami arrival time, consider planning for vertical evacuation to levels above tsunami flow depths in reinforced concrete buildings with deep foundations (those with reinforcing and foundations typical of Japan/California/New Zealand earthquake building codes).
LINKS:
Pacific Tsunami Warning Centre: http://ptwc.weather.gov/
Indian Ocean Tsunami Warning and Mitigation System (ICG/IOTWMS), more information at http://www.ioc-tsunami.org/index.php?option=com_content&view=article&id=8&Itemid=58&lang=en
North-Eastern Atlantic, Mediterranean, and connected seas: Tsunami Information Centre. http://neamtic.ioc-unesco.org/
Tsunami evacuation: lessons from the Great East Japan earthquake and tsunami of March 11th, 2011http://shop.gns.cri.nz/sr_2012-017-pdf/
Guidelines for Design of Structures for Vertical Evacuation from Tsunamishttps://www.fema.gov/media-library-data/1426211456953-f02dffee4679d659f62f414639afa806/FEMAP-646_508.pdf
Designing for tsunamis (including vertical evacuation buildings) http://www.preventionweb.net/files/1505_DesigningforTsunamis.pdf
- INSURANCE : Consider purchasing insurance to cover potential losses to the project. While insurance does not prevent injuries or deaths, or save communities, it can certainly reduce financial losses and enable the project to recover from the effects of the earthquake and regain its function more quickly. More information
CONTEXT:
- The high tsunami risk in the area of your project means that you should consider specific risk transfer measures to protect the project.
- A tsunami risk assessment by an expert should be conducted first.
- If natural hazards are not considered effectively in project siting, design, construction, and operation then the potential exists for partial or complete loss of the investment and exposing of the workforce to unnecessary risk.
MITIGATION:
- Utilize risk transfer methods such as insurance, to cover potential losses to the project, if the hazard cannot be avoided.
- Consider purchasing catastrophe insurance to cover potential losses on the project. Cataastrophe insurance may be available from the government or from private insurers. Insurance can help provide funds after a tsunami, to help in reconstruction and replacement of damaged buildings, contents or other project components. This can ultimately enable the project to recover from the effects of the tsunami and regain its function more quickly. However, it is important to note that insurance only provides coverage for financial losses, but cannot prevent damage, business interruption, injuries or deaths.
LINKS:
Insurance against Losses from Natural Disasters in Developing Countries: https://www.researchgate.net/profile/Reinhard_Mechler/publication/265286458_Insurance_against_Losses_from_Natural_Disasters_in_De-veloping_Countries/links/54ac53150cf21c477139d8c3.pdf
Insurance-related instruments for disaster risk reduction - http://www.preventionweb.net/english/hyogo/gar/2011/en/bgdocs/Suarez&_Linnerooth-Bayer_2011.pdf
