Tsunami risk reduction in Central America for building disaster resilience
In the last 500 years, Central America has suffered more than 50 large-scale tsunamis that have affected the Pacific and Caribbean coasts and left behind a legacy of death and destruction. The increase of coastal population in recent decades led to higher total exposure to tsunamis, and economic and institutional dysfunctions have added vulnerability, leaving the poorest communities facing a higher risk for coastal hazards in general, including tsunamis. These facts lead to an urgent need for effective tsunami risk management in Central America through enhanced regional cooperation. This is particularly true for transboundary natural hazards like tsunamis.
On September 6, at 6:16 PM local time, an earthquake occurred off the coast of Nicaragua in 1992. Some damage was reported in Costa Rica but most of it affected Nicaragua, with at least 116 people killed and several more injured. It demonstrated that in Central America local seismic sources have potential to generate large tsunamis. After this event, several key stakeholders including the Coordination Centre for the Prevention of Natural Disasters in Central America (CEPREDENAC) promoted studies of tsunamis in the region to protect coastal residents from this natural phenomenon. A further positive boost for tsunami preparedness in the region was the establishment in 2009 of a dedicated Working Group for Tsunami Warning and Mitigation in the Pacific coast of Central America. It was the initiative of the Intergovernmental Coordination Group for the Pacific Tsunami Warning and Mitigation System (ICG/PTWS), an intergovernmental body under the Intergovernmental Oceanographic Commission of UNESCO (UNESCO/IOC). ICG/PTWS focuses on commitments of member states to continually embrace the comprehensive nature of tsunami risk reduction.
Technically, a tsunami warning system uses seismic monitoring to determine location, depth, and magnitude of an earthquake, further predicting tsunami arrival time and expected tsunami waves heights when they hit the coast. An efficient and effective tsunami warning system requires proper analysis of seismic, and also sea level and other observational data. With the support of UNESCO/IOC, and substantive national contributions, the establishment of some national seismic networks have been advanced. Currently more than 350 seismic stations in Central America provide data for tsunami warning purposes. Limited coverage in the eastern region of Nicaragua, Honduras and northwest of Panama remains. Real-time data sea level networks are another critical component of tsunami warning systems. Through the ICG/PTWS and its equivalent in the Caribbean, as well as the Global Sea Level Observing System, IOC-UNESCO has improved the sea level monitoring capabilities to some extent. However, not all countries are operating comprehensive sea level stations in the region. Leaders at regional level are the Ministry of Environment and Natural Resources (MARN) of El Salvador, National Tsunami Monitoring System (SINAMOT) of Costa Rica, Institute of Geosciences at the University of Panama and Nicaraguan Institute of Territorial Studies (INETER).
It takes much more than just technique to build a tsunami warning and mitigation system.
Hazard and risk assessment for tsunamis and other coastal hazards is a key element for any tsunami warning system. In the last decade, significant improvements have been made in understanding the regional tectonic setting, distribution of the major seismic faults and identifying credible sources of tsunamis that could affect potentially the Pacific and Caribbean Coasts of Central America. It has enabled updating and enlarging existing tsunami hazard maps building on the existing CEPREDENAC previous efforts. All these developments can be used for numerical tsunami modeling, evacuation mapping, planning and exercises. So far, ten sources were defined and some of them conformed by several fault segments. Four near-field sources extend throughout Guatemala to Panamá in the Pacific margin, and three sources from Costa Rica to Panamá along the Caribbean margin. In the far field, one source has been suggested along the Colombia-Ecuador subduction zone, and two sources in the Colombia-Venezuela South Caribbean Deformation Belt. Most of historical tsunamis at both shores were triggered by earthquakes located in the Middle American Trench and the Northern Panama Deformation Belt.
Tsunami Warning System should be integrated with existing and planned coastal hazard mitigation and preparedness system. Tsunami preparedness in Central America is improving in varying degrees of development. Some countries have established National Tsunami Warning Systems and National Tsunami Warning Centers. A Regional Tsunami Advisory Center at INETER in Nicaragua is under development, the Central American Tsunami Advisory Center (CATAC), which has succeeded to obtain technical assistance and financial support by the Japan International Cooperation Agency (JICA), and contributions from other regional institutions and organizations.
To enhance public awareness and community preparedness a new course focusing on Tsunami Evacuation Maps, Plans, and Procedures was hosted in Honduras from 2015-2017, piloted by the Permanent Commission of Contingencies (COPECO) and conducted under the ICG/PTWS, with strong leadership of the International Tsunami Information Center (ITIC) by USA. At the community level, serious efforts of tsunami preparedness are conducted in Honduras, Costa Rica and Nicaragua, including through participation at Pacific and Caribbean Tsunami Wave Exercises and national and local tsunami evacuation drills to evaluate the quality of the Standard Operating Procedures (SOP), communication lines, and community’s responses. The community of Tortuguero in the northern Caribbean coast of Costa Rica, the community of Cedeño in the Pacific coast of Honduras, Omoa in its Caribbean coast, and Pochomil, Masachapa and Corinto in Nicaragua’s Pacific coast are good examples of communities that are ready to respond in case of tsunami.
Other donors addressing disaster risk reduction have allocated financial support in this region to empower vulnerable communities and build resilience of national systems to prepare for and respond to a wide variety of natural hazards. The European Commission Humanitarian Aid Department's Disaster Preparedness Programme (DIPECHO) puts disaster risk reduction as its priority in Central America since 1994. This program has funded many projects on emergency infrastructure support, development of risk maps, establishment of early warning systems, and community preparedness. One project targeted on ‘Strengthening Early Warning Systems in Central America from a multi-threat perspective’ was implemented during DIPECHO VI, noting that the region needs a coordinated regional platform to address the issue of early warning. In the same line, it has now funded the project “Building resilient communities and integrated Early Warning Systems for tsunamis and other ocean related hazard in Central America” (2016-2017), with focus on El Salvador, Guatemala, Honduras and Nicaragua.
The work on tsunami risk reduction in Central America has yielded many results in saving lives and supporting the local, regional and national disaster prevention and response institutions to increase their capacity to face emergencies, benefiting millions of residents in this region. By providing technical support to countries in the Central American region and developing proposals for tsunami topics, IOC-UNESCO works side by side with relevant government organizations, institutions and local communities to put unremitting efforts to protect the life and property safety when confronting the attack of tsunamis.