Implementation of tsunami warning procedures in the Caribbean in case of a volcano crisis: Use of a Volcano Notice for tsUnami Threat (VONUT)

While 80% of tsunamis are related to earthquakes, recent examples of the Hunga Tonga Hunga Ha’apai (2022) tsunami as well as others from the Kick’em Jenny (2015), Saint Vincent (2021), and La Palma (2021) eruptions have sparked renewed reflection on how a tsunami warning system could also handle non-seismic tsunami events. A warning system is usually based on intrinsic and automatic detection by an instrumental network. In the case of tsunamis generated by earthquakes, it is the data from seismic stations and pre-established location and magnitude criteria that trigger actions from the Tsunami Service Providers (TSP, i.e., regional centers for threat information). Realtime sea level data then help constrain forecasts and determine the end of the threat. However, tsunamis generated by volcanic events are different from those induced by earthquakes in terms of source, detection, messaging, and modeling. In the Caribbean and Adjacent Regions, the UNESCO/IOC Intergovernmental Coordination Group for Tsunami and other Coastal Hazards Warning Systems created a task team to develop tsunami procedures in the case of a volcano crisis. We present here the recent progress of the task team. A bulletin is proposed to be issued by volcano observatories to the Tsunami Service Providers in the case of a potentially tsunamigenic volcano event. Derived from a Volcano Observatory Notice for Aviation (VONA) bulletin, this proposed VONUT bulletin, (Volcano Observatory Notice for tsUnami Threat), is under construction in collaboration with Caribbean volcano observatories and the Pacific Tsunami Warning Center, the TSP for the Caribbean. It was tested during the annual tsunami exercise CARIBE WAVE 2023, which includes testing the communications between the Tsunami Service Provider and nationally designated tsunami authorities. However, much more work is required to get a full operating warning system, as volcano scenarios and subsequent tsunami waves remain highly challenging to model and scale.