The term 'HHHHH' can be solved as 'ETAS', which is an acronym for the European Tsunami Warning System. This system was established in 2005 and is a collaboration between the European Union and the Intergovernmental Oceanographic Commission of UNESCO. It is responsible for providing early warnings of tsunamis in the Mediterranean Sea, the North-East Atlantic, and the adjacent seas. The system is composed of a network of seismic stations, tide gauges, and other instruments that monitor the ocean floor for signs of potential tsunamis.