Coastal Communities Tsunami-Resilient by 2030

During the UN Ocean Conference between 27 June to 1 July 2022 in Lisbon, Audrey Azoulay, Director-General of UNESCO, announced that they plan to make coastal communities “Tsunami Ready” by 2030.

The program’s main objective is to help improve coastal communities’ preparedness for tsunamis and minimize the loss of life, livelihoods, and properties. These can be achieved by fulfilling the 12 indicators established by the programme to evaluate and reduce the risk of, prepare and respond to tsunamis (UNESCO/IOC Tsunami Ready, 2022).

Azoulay notes, “The global tsunami warning system, led by UNESCO, is particularly effective in detecting tsunamis very quickly. But sounding the alarm is not enough: coastal communities must also be trained to respond correctly to save lives. UNESCO is now strongly committed to training them worldwide by 2030.”

According to the UNESCO press release, a coastal community “must develop a tsunami risk reduction plan, designate and map tsunami hazard zones, develop outreach and public education materials, create public-friendly tsunami evacuation maps, and publicly display tsunami information” to become tsunami ready.

Tsunami risks

Although tsunamis are rare, they are happening more than we usually expect. The press release says that UNESCO’s Pacific Tsunami Warning Centre, hosted by the United States, has responded to 125 events, an average of 7 per year.

It is commonly thought that only the Pacific and the Indian Ocean regions are at risk of tsunamis. However, statistic shows that there is a 100% chance that the probability of tsunami wave above 1 meter in the next 30 years will occur in the Mediterranean and will be driven by volcanic activity and landslides at 10%, and by meteorological events like rain, tornadoes, and hurricanes at 2%.

To date, UNESCO’s Tsunami Ready Programme was piloted in forty communities across 21 countries in the Caribbean, Pacific, and Indian Ocean regions, with plans to extend this to thousand more vulnerable communities worldwide. As tsunamis impact communities differently, tsunami plans should also reflect this and tailor them according to local risk factors. To help these communities, UNESCO will mobilize “significant financial resources by leveraging important partnerships”, says Vladimir Ryabinin, Executive Secretary of the UNESCO Intergovernmental Oceanographic Commission.

Key partners for this initiative include the United Nations International Strategy for Disaster Reduction (UNDRR) and the European Union, Australia, Japan, Norway, and the United States.

Climate change and Tsunamis

Is there a link between the climate crisis and tsunamis? Will climate change increase the threat of tsunamis? The article from The Conversation, “5 ways climate change increases the threat of tsunamis, from collapsing ice shelves to sea-level rise”, presents five climate-related events that could trigger more tsunami occurrences.

The article says that although earthquakes and volcanic eruptions are the most significant drivers of tsunamis at about 15%, as what happened in Tonga after their volcano, Hunga Tonga-Hunga Ha’apai, erupted. Other events like climate change can increase tsunami incidents.  

Rising temperature is causing more frequent and intense storms and cyclones, melting glaciers and ice caps, and sea-level rise, which can trigger tsunamis because of their impact on the Earth’s crust.

The article highlights five climate-linked geological changes that can increase the incidence of earthquakes and volcanic eruptions, which, in turn, can exacerbate the threat of tsunamis.

1. Sea level rise. Even a modest rise in sea levels can dramatically increase the frequency and intensity of flooding in case of tsunami events, as waters can travel further inland. The article cites a 2018 study showing that a 50-centimetre rise would double the frequency of tsunami-induced flooding in Macau, China. This means that smaller tsunamis in the future will have the same impact as more enormous tsunamis would today.
2. Landslides. “A warming climate can increase the risk of both submarine (underwater) and aerial (above ground) landslides, thereby increasing the risk of local tsunamis.”
   
   The melting of permafrost decreases soil stability making it more susceptible to erosion and landslide. Heavier rains can also trigger landslides as climate change makes storms more frequent.
   
   Landslides trigger tsunamis through the impact it creates upon entering the body of water or through rapid underwater landslides. This happened in Alaska in 2015 when melting permafrost and glaciers exposed unstable slopes, sending 180 million tonnes of rock into a narrow fiord and generating a tsunami reaching 193m high – one of the highest ever recorded worldwide.
3. Iceberg calving can generate tsunamis as chunks of ice fall into the ocean. “Wandering icebergs can trigger submarine landslides and tsunamis thousands of kilometres from the iceberg’s source, as they hit unstable sediments on the seafloor.”
4. Volcanic activity from ice melting. This relates to the changes in stress on the Earth’s crust as the ice is removed, a phenomenon known as “isostatic rebound”, or the long-term uplift of land in response to the removal of ice sheets. Isostatic rebounds can trigger volcanic activity and associated hazards that can cause tsunamis.
5. Increased earthquakes due to the isostatic rebound or land uplift. As the ice melts, weight is being lifted that has suppressed fault movement, causing the crust to shift as it adjusts to weight loss. This phenomenon is already observed in Alaska. Melting glaciers induces many small earthquakes and is thought to have caused the magnitude 7.2 St Elias earthquake in 1979.

Also, the low pressure linked to storms and typhoons can trigger earthquakes in areas where the Earth’s crust is already under stress, as some studies have shown. This phenomenon was observed in eastern Taiwan during the analysis of their earthquakes between 2002 to 2007.

As climate events increase the likelihood of tsunamis, the article suggests that climate mitigation strategies should include elements that improve tsunami preparedness, such as what UNESCO is doing.