Central America is a small and culturally homogeneous region that, since the 1990s, has experienced economic and political integration of its six countries, which share the same threats of volcanic eruptions, disastrous earthquakes and tsunamis. The Pacific coastline of 1700 km is common for Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama, and the Pacific subduction zone has the potential for creating huge tsunamis that threaten this coast. In addition to the natural hazard, the growing tourist industry is expanding its infrastructure along the Pacific beaches, which again enhances the exposure and tsunami risk. Even though the 1992 tsunami disaster in Nicaragua did not severely hit the tourist beaches, it raised the risk awareness, and special attention is now given to ‘slow’ earthquakes that may be modest in shaking while still having a large tsunami potential. The tsunami hazard mapping is well advanced in Nicaragua, Costa Rica and El Salvador, and initiatives are ongoing to improve the mapping in all countries. National systems for early warning were established in Nicaragua and El Salvador, while the other four countries rely on rapid information from the Pacific Tsunami Warning Center. Mitigation measures and information campaigns are presently conducted on a national basis in all countries, but a regional centre for early tsunami warning and coordinated information campaigns (CATAC) is expected to become operational in the near future.

Tsunami warning traditionally has been perceived within the scientific community as an essentially deterministic process. This may be satisfactory in regions where tsunami monitoring is very extensive and the uncertainty in tsunami forecasting is low. However, where there is significant uncertainty, the worthy aspiration to achieve a zero-tolerance policy on tsunami fatalities is set against the reduction in public alert compliance associated with previous false alerts. A risk-informed approach is presented, which outlines a decision process that allows for a decline in alert compliance due to false alerts. This risk-informed approach assesses probabilistically the tsunamigenicity of fault rupture, using data not just from historical catalogues but also the geological record. Prior probabilities could be automatically updated in real time by a Bayesian Belief Network from observations obtained in real time: earthquake depth information; pressure sensor recordings, tide gauge measurements; or visual reports of coastal inundation. A decision to issue a general evacuation warning in a specific region might be made provided the updated posterior probability reached a critical threshold.