Tsunamis are a series of large ocean waves generated by major earthquakes beneath the ocean floor or major landslides into the ocean. When the waves enter shallow water, they may rise to several feet or, in rare cases, tens of feet, striking the coast with devastating force. The first wave in a tsunami may not be the largest, and even waves only 1 or 2 feet high still have the capacity to move large debris, pushing it inward and causing damage and loss of life. People on the beach or in low coastal areas need to be aware that a tsunami could arrive within minutes after a severe earthquake. The tsunami danger period can continue for many hours after a major earthquake and a tsunami can occur during any season of the year and at any time, day or night. Although a tsunami cannot be prevented, the impact of it can be mitigated though proper community preparedness, timely warnings, and effective response. [Source: NOAA]
How do I prepare?
Learn risks: if you are new to an area, call your local emergency management office and be briefed on warning signs.
Tsunami natural warning signs:
- You may feel it. A strong coastal earthquake that lasts more than 30 seconds serves as a natural warning sign. Protect yourself first, then survey area and evacuate quickly inland and move to higher ground. When wave arrival is eminent, move to higher ground, or upper levels of strongly reinforced, concrete, multi-floor buildings
- You may see it. A rapid, unusual ocean change, such as receding waves exposing the sea floor.
- You may hear it. A loud “roar” from an approaching tsunami is often heard.
Make a Family Emergency Plan: include contact information to use if you family is not together when a tsunami occurs, as well as information on how to get back together.
Make sure you have a battery-powered or hand crank radio, along with spare batteries if applicable, to receive updates.
Be ready to evacuate: all coastlines are vulnerable to tsunamis. Make sure you know your communities tsunami hazard and evacuation zone. Walk your tsunami evacuation routes so you know where they are located.
Businesses and employers play a key role in ensuring preparedness for both their staff and surrounding community. They may consider the following when preparing their workplace for a tsunami:
- Learning the risks associated with tsunamis, how they occur, and natural warning signs.
- Researching where their business is located in relation to hazards. If their business lies within or along a tsunami evacuation zone, preparedness steps are crucial.
- Determining what the primary risks to their business would be. This may include on-site staff and customer safety, merchandise/stock, and major investments.
- Posting maps and training employees on evacuation routes, highlighting the safest and quickest way to higher ground. These plans may include meeting locations and how to check-in with co-workers.
- Developing communication plans with employees with alternatives to cell phone usage as signals may be lost during a tsunami.
- Investing in disaster evacuation kits.
- Keeping accurate inventories and understanding exactly what is and is not covered by insurance plans, if applicable.
- Backing up important data, as well as copying and scanning important documents to be stored off-site.
- Marking items and filing cabinets to distinguish which are top priority to be removed first after a tsunami subsides or prior to a tsunami striking, if adequate warning time is given.
- Planning with local authorities if their business has the potential to leak hazardous materials into the environment during and after a tsunami.
Additionally, consider creating a or revising your current workplace's Business Continuity Program.
By educating residents on when and how to evacuate for tsunamis, assisting local government to be prepared to coordinate and mobilize the evacuations and generating awareness of safe community development practices to lessen the destruction caused by tsunamis, community organization plays a critical role in increasing community resilience to a tsunami. While every community may need a different approach when preparing for a tsunami, below are some basic steps that can be taken by community organizers to promote tsunami awareness.
- Learn the basics of tsunami behavior and promote educational awareness.
- Organize your efforts based on what your community needs are and on the partners and resources that are available to help.
- Make hazard and evacuation maps to guide all your tsunami preparedness efforts.
- When planning evacuation routes, if possible, pick areas 30 meters (100 feet) above sea level or 3 milometers (2 miles) inland, away from the coastline. Individuals should be able to reach their safe location on foot within 15 minutes. If impossible to reach the areas before a tsunami, every foot inland or upward may make a difference.
- Involve the community in tsunami preparedness to educate everyone about evacuations and things they can do to increase community safety. Reach out to vulnerable populations and businesses as well as neighborhood groups.
- Learn about what makes official tsunami warning systems effective and advocate to improve your community’s system, if needed. Working with the local government can be beneficial and save lives.
- Determine whether and how your community can take long-term steps to reduce damage from tsunamis.
- Organize a Tsunami Buddy System and encourage community members and neighbors to take part.
The most important thing your community should do is be ready to evacuate quickly and safely all areas that could be flooded by the tsunami. Therefore, encourage community members to know the height of their street above sea level and distance of their street from the coast. Evacuation orders may be based on these numbers and knowledge of such is crucial if orders are given. [Source: GeoHazards Intl]
Local and National Government
While most tsunami events occur in the Pacific and Indian oceans, any costal community and its government should consider taking steps to prepare for a tsunami. Establishment of an effective warning system is one of the most critical preparedness action that can provide the needed alerts to community members to seek higher ground or evacuate inland from the coast. Furthermore, here are some tips and advice for Local and National Governments on tsunami preparedness:
- Test regularly and, if needed, upgrade warning systems.
- Keep evacuation routes up-to-date and clearly marked. New land developments, whether residential, commercial, or industrial, should be incorporated into exisiting evacuation routes if they lie within the tsunami hazard zone. Share the evacuation routes and procedures widely throughout the community.
- Partner with local Red Cross chapters and emergency management agencies who may have upcoming community events in which you could share tsunami preparedness messages and hand out informational brochures.
- Invite local disaster preparedness practitioners to provide tips on hurricane preparedness and explain the natural warning signs of a tsunami for the local population.
- Publish a special section in local newspapers with emergency information on tsunamis and information on where/how warnings will be administered. This section may include where to find evacuation routes and phone numbers of local emergency services offices, local Red Cross chapters, and the nearest hospitals.
- Pitch tsunami preparedness tips to radio and television stations, as well as post these tips immediately on local and national government websites. In addition, ensure continuity of service delivery messages.
- Take part in Tsunami Preparedness Week and plan your own outreach and preparedness events during it to garner more interested and publicity.
What do I need to know?
The recent development of real-time deep ocean tsunami detectors and tsunami inundation models have given some coastal communities the tools they need to reduce the impact of future tsunamis; however, one should not wait for the official warnings to act, rather familiarize themselves with the natural warning signs of tsunamis and act immediately. When coast earthquakes occur, it may be only minutes before the tsunami arrives Remember, in a local event, the natural warning signs are your earliest and possibly only alert.
Tsunami: Tsunamis are ocean waves produced by earthquakes or underwater landslides. The word is Japanese and means "harbor wave," due to the past devastating effects these waves have had on low-lying Japanese coastal communities. Tsunamis are often incorrectly referred to as tidal waves, but a tsunami is actually a series of waves that can travel at speeds averaging 450 miles per hour in the open ocean. In the open ocean, tsunamis are not felt by ships because the wavelengths are hundreds of miles long, with an amplitude of only a few feet--this would also make them unnoticeable from the air. As the waves approach the coast, their speed decreases and their amplitude increases. On rare occasions, wave heights have been known to be over 100 feet high; however, waves that are 10 to 20 feet high can be very destructive and cause deaths and/or injuries. As these waves approach coastal areas, the time between successive wave crests varies from 5 to 90 minutes. The first wave is usually not the largest in the series of waves, nor is it the most significant. Furthermore, one coastal community may experience no damaging waves while another, not that far away, may experience destructive deadly waves. Depending on a number of factors, some low-lying areas could experience severe inland inundation of water and debris of more than 1,000 feet. [Source: NOAA]