The IOC Intergovernmental Coordination Group for the Indian Ocean Tsunami Warning and Mitigation System (ICG/IOTWMS) at its 14^th session (Banten, Indonesia, 17–19 November 2024, decided to organise an Indian Ocean Wave Exercise in 2025 (IOWave25) and established a Task Team to plan and conduct the exercise.

IOWave25 will again simulate Indian Ocean countries being put in a tsunami threat situation. As a primary objective it will require the National Tsunami Warning Centre (NTWC) and the National and/or Provincial and/or Local Disaster Management Offices (NDMOs/PDMOs/LDMOs) in each country to implement their Standard Operating Procedures (SOPs) associated with their national tsunami warning chains. The exercise will test the preparedness for responding to tsunamis generated by seismic events (undersea earthquakes) and for the second time a non-seismic (volcanic) event. Pre-exercise training workshops for Member States will be organised in July - August 2025. This will help ensure national tsunami warning chains and associated SOPs are reviewed to help prepare Member States for IOWave25 and any future real tsunami events.

In addition to testing the SOPs and communication links at all levels of the national tsunami warning chain, another primary objective of IOWave25 is to enhance tsunami preparedness at the community level. To this end, IOWave25 will also provide an opportunity for Member States to test the UNESCO-IOC Tsunami Ready Recognition Programme (TRRP) indicators or other related national initiatives in at-risk communities, where implemented. A self-paced training course on UNESCO-IOC Tsunami Ready is available through the Ocean Teacher Global Academy (see https://oceanexpert.org/event/4610 for further information). An introduction to Tsunami Ready for ICG/IOTWMS Member States was provided at the Workshop on Tsunami Evacuation Maps, Plans, and Procedures and UNESCO-IOC Tsunami Ready Recognition Programme held in Hyderabad, India during 15–23 April 2025 (https://oceanexpert.net/event/4662).

Dates and Scenarios: IOWave25 will comprise four scenarios with simulated tsunami waves travelling across the Indian Ocean basin. Member States are invited to participate in one or more events, which will be run in real-time:

• Scenario 1 - Sunda Trench starting at 01:00 UTC on 25 September 2025 (Thursday): Magnitude 9.0 earthquake in Sunda Strait, Indonesia. 
• Scenario 2 - Makran Trench starting at 06:00 UTC on 15 October 2025 (Wednesday): Magnitude 9.0 earthquake in the Makran trench off the coast of Pakistan.
• Scenario 3 - Fani Maore Volcano starting at 15:00 UTC (eruption at 14:00 UTC) on 25 October 2025 (Saturday): Tsunami generated by volcanic eruption at Fani Maore in the Mozambique Channel between Madagascar and the eastern coast of Africa. 
• Scenario 4 - Sumatra Trench starting at 03:00 UTC on 05 November 2025 (Wednesday): Magnitude 9.2 earthquake in Northern Sumatra, Indonesia.