Further Challenges for Warnings of Tsunamis – A Satellite Activity for the UN Ocean Decade Safe Ocean Laboratory

Tsunamis are one of the most deadly and difficult natural hazards to warn for and to respond to. In addition to the most typical types of tsunamis generated by undersea earthquakes along subduction zones, there are what we term “non-seismic tsunamis” and “complex tsunamis”. These may be generated by landslides and submarine landslides generated by volcanic eruptions or earthquakes not necessarily associated with subduction zones. 

A webinar addressing the challenges for warnings of non-seismic and complex tsunamis was organized by the UNESCO/IOC Secretariat for the Intergovernmental Coordination Group for the Indian Ocean Tsunami Warning and Mitigation System (ICG/IOTWMS) and Indian Ocean Tsunami Information Center (IOTIC) during 6-7 April 2022. The event contributed to the UN Ocean Decade Safe Ocean Laboratory as a satellite activity.

The webinar explored the current knowledge of non-seismic and complex tsunamis, the ability to monitor their generation and warn for their likely impacts to save lives, and pathways for improving future warnings. Session A, which focused on learning from recent tsunamis generated by non-seismic and complex sources, was attended by 207 participants from 43 countries. Session B, which focused on knowledge and gaps to warn for such tsunami events, was attended by 166 participants from 46 countries.

Videos of both sessions are available to view here.

For non-seismic and complex tsunamis with longer travel times, the end-to-end response from the warning centres through to the communities at risk is very important. Warning centers are currently investigating methods based on sea level observations as the main indicator of tsunami generation. The addition of targeted local monitoring infrastructure, such as seismic arrays, would also be beneficial. The development of standard operation procedures for tsunami response across all levels is important for a successful end-to-end response from the warning centres through to the communities at risk.

Many of the non-seismic and complex tsunamis result in local inundation leaving very little time for detection and warning. Thus, community awareness and preparedness are paramount. The UNESCO/IOC Tsunami Ready Programme is currently being adopted by coastal communities to prepare for non-seismic and complex tsunamis (as well as the typical types).

Tsunami Ready is a community performance-based programme based on a set of indicators, that facilitates tsunami preparedness as an active collaboration of the public, community leaders, local and national emergency management agencies. The programme includes identification of the local tsunami hazards, community evacuation based on natural warnings as well as official warning, and the development of standard operation procedures for tsunami response across all levels.