Tsunamis are triggered by sudden events that displace large volumes of water. They are long waves that most frequently originate from earthquakes, setting the entire water column in motion, allowing the tsunami to propagate far from the source, in some cases, travelling entire oceans before striking land with potentially devastating force.
The scale of this hazard was tragically revealed in 2004, when an Indian Ocean tsunami killed more than 225,000 people and affected millions across Indonesia, Sri Lanka, India and Thailand, making it the deadliest tsunami in recorded history. For scientists working on natural hazards, the disaster exposed a critical gap: although tsunami research existed, there was no shared global framework to understand, compare and communicate tsunami risk. “The 2004 tsunami was a turning point,” recalls Finn Løvholt, Vice-Chair of the COST Action accelerating global science in tsunami hazard and risk analysis (AGITHAR) and rapporteur of the Global Tsunami Model Board. “It showed that we lacked a shared scientific framework to understand and assess the risk.” This realisation set in motion years of international collaboration and ultimately led to the creation of the Global Tsunami Model (GTM) Association.

Where collaboration took shape

COST Action AGITHAR brought together a diverse international community to share probabilistic approaches to tsunami hazard and risk assessment and advance understanding of both seismic and non-seismic tsunami sources.
The Action addressed key research gaps and produced highly visible, frequently cited outputs, including the first comprehensive reference, Probabilistic Tsunami Hazard and Risk Analysis – A cookbook. Its results extended well beyond academia, informing early warning systems, mitigation planning and policy discussions, and were presented to international bodies such as UNESCO, United Nations Office for Disaster Risk Reduction (UNDRR), European Civil Protection and Humanitarian Aid Operations (DG ECHO) and the World Bank.

AGITHAR also had a strong impact on networking, with partners involved in several funded interdisciplinary R&D projects contributing tsunami expertise. These projects received more than €40 million in research investment.

By contributing to turning fragmented research into a shared, operational framework for tsunami risk, AGITHAR created the scientific, technical and community foundations needed to transition from cooperation to long-term implementation.

From ideas to institutions

As the Action came to an end, a key question remained: how could this collective expertise be sustained and reliably made available to society? The answer came through the COST Innovators Grant (CIG) Sustaining AGITHAR – building a Global Tsunami Model Association. With support from the COST Innovators Grant, researchers moved beyond a temporary network to build a permanent structure. This led to the establishment of the Global Tsunami Model Association in 2024, which was legally recognised as an independent entity on 1 August 2025.

“It was important to create the GTM to provide a more structured approach to tsunami hazard and risk analysis globally,” explains Jörn Behrens, Chair of AGITHAR and GTM Board. “Tsunami hazard is highly interdisciplinary, with few standardised procedures, and the community needs to have an institutional home to support permanent improvement of community tools and knowledge.”

The ambition of GTM is clear, though challenging: to assess tsunami risk in a consistent, transparent and globally comparable way. Over time, the Association will deliver shared guidelines for hazard and risk analysis, alongside a technical core producing reference datasets. In practice, this will mean common models, agreed workflows and openly accessible knowledge to support decisions from local coastal planning to global policy discussions. “We’re trying to provide a global template for tsunami hazard and risk assessment. When everyone views the data in the same way, it becomes easier to plan, prioritize, and save lives,” says Clea Denamiel, AGITHAR participant and member of the GTM Board.

Although the Association is still at an early stage, concrete progress is already underway. GTM is actively developing global hazard and risk models and related services, with early prototypes in place and discussions ongoing about how these could evolve into operational tools. While no models have yet been commercialised, prototype models exist and it is expected that practical applications will emerge as the organisation matures.

From science to global preparedness

The Global Tsunami Model Association is designed to serve society as a whole, not only the scientific community. Its audiences include national and local authorities, civil protection services, tsunami early warning providers, international organisations such as the United Nations and the World Bank, as well as private actors including insurance and reinsurance companies. By acting as a neutral scientific reference point, GTM enables all these users to work from the same trusted evidence base.

The long-term vision is firmly focused on public benefit. “We can’t predict when and where the next big wave will occur, but we can contribute to an improved understanding of the risk posed by tsunamis. That provides a much better basis for making wise decisions before something happens,” says Stefano Lorito, AGITHAR participant and member of the GTM Board. By creating a permanent home for collaboration, common standards and shared models, the CIG ensured that AGITHAR’s impact did not end with the Action. Instead, it continues through the Global Tsunami Model Association — a lasting COST legacy that turns scientific cooperation into global preparedness and resilience. “The goal is for the world to be better prepared for the next major tsunami,” adds Alexander Rudloff, AGITHAR advisory board member and treasurer of the GTM Board.“The more knowledge we share, the better societies can adapt and protect themselves.”

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(Source: Tsunamis: Facts About Killer Waves | National Geographic)