Detail from the 1:25,000 map of seismic micro-zoning of the Santo Domingo urban area, showing the Distrito Nacional.
The 2010 earthquake in Haiti was a devastating reminder of the exposure of the island of Hispaniola, which lies on a tectonic fault zone, to severe seismic risks. Like Haiti, the Dominican Republic has many highly vulnerable built-up areas.
The BRGM, which has been working for twenty years in the Dominican Republic on projects ranging from geological mapping to natural risk prevention and the mining environment, contributed to a wide-ranging seismic risk assessment in 2014-2016, mainly funded by the European Union and managed by the United Nations Development Programme (UNDP).
The Santo Domingo urban area extends for over 260km2 and has a population of some 3 million people. Because of the nature of the terrain, many sectors are highly vulnerable to potential amplification of seismic tremors, with major risks of collapse and soil liquefaction. Inappropriate building techniques and poor urban planning are contributing to the problem.”
Mapping, assessments and risk prevention
The project involved several complementary activities to address this situation. The BRGM focused in particular on seismic risk assessments at the local and regional scales. A reassessment of the characteristics of potentially active fault zones and updating of the catalogue of historic data and survey results provided a basis for calculating the regional seismic risk level, which, although significant uncertainties remain, resulted in a level slightly above the threshold for earthquake-resistant construction set out in Dominican building regulations.
A seismic microzoning campaign was undertaken to classify urban areas according to the local risk level. Because the nature of the subsoil varies, the destructive potential of an earthquake can be radically different from one neighbourhood to the next.
BRGM teams also studied the vulnerability of residential buildings in the Distrito Nacional in central Santo Domingo, which includes the Zona Colonial and its highly vulnerable architectural heritage. According to the simulations run, earthquake damage would affect a large part of the zone, with a great many building becoming uninhabitable and thousands of people made homeless.
The BRGM and its partners put forward preventive measures developed in cooperation with the Dominican civil protection authorities. The project also included a major component on communication to the public, as well as skills transfers, particularly for young geologists and engineers working for the national geological survey.
Using the MASW acquisition method (Multichannel Analysis of Surface Waves) in Santo Domingo.
The signals generated by a hammer blow on a piece of wood are recorded by a battery of 24 geophones.
© National Geological Survey of the Dominican Republic - Ing. Santiago Muño