CGS Foreign Development Cooperation

El Salvador

Geological studies of natural hazards, El Salvador

The geological conditions and the degree of vulnerability in geologically complex and economically important areas have been studied, including fi ve Salvadorian islands in the sensitive border area of the Gulf of Fonseca, and other regions north of the country’s capital. Geology, geomorphology, and the impact of human activity are the main factors that affect the type and extent of risks in the selected area. This multidisciplinary project has included geological mapping, the study of geodynamic processes, volcanological analysis, studies of the youngest deposits, and geological engineering.

The field work consisted of several operations involving geological mapping and the compilation of a map in 1:50,000 scale. This map has served as a basis for further activities. Modern mapping had not been conducted in either country, since international projects in Central America are usually short-term studies. Our projects are regional, and therefore cover large areas by uniform methods. Geological maps provide useful information for interpreting geomorphology. They are also crucial in the creation of maps and reports on geological hazards, including risk evaluation, locating vulnerable areas, specifying the kinds of risks and their potential prediction. The results are provided to local authorities in
GIS and printed forms.

El Salvador is frequently affected by natural disasters that are closely related to geological conditions (hurricanes, landslides, rock falls, fl oods, and volcanic and seismic activity). For such a small and densely populated country, the risk assessment data are very important. Loss of life, damage to infrastucture and private property, the destruction of agricultural areas, and the disruption of the lives of thousands of people are the common results of such events. This is why the study and prediction of natural hazards have priority.

The activities of the Czech Geological Survey in El Salvador began in 2003, in cooperation with the newly established governmental institution SNET (Servicio Nacional de Estudios Territoriales). During two periods of research, new data were acquired from the easternmost region of the country, from the Salvadorian islands in the Gulf of Fonseca, and from central El Salvador. Geological and structural patterns are highly complicated in these vulnerable areas, where various stages of weathering and the tectonic deformation of volcanic rocks signaled diverse types of risks. In 2004 the field work was supplemented by remote sensing evaluation.

The new data serve the purposes of land planning and evaluating the most endangered areas. They are also of use to the Civil Defense for making evacuation plans, as well as for general education.