The driving force for great earthquakes and the cycling of water and climate-influencing volatiles (carbon dioxide, sulfur, halogens) across the convergent margin of Central America have been a focus of international efforts for over 8 years, as part of the MARGINS program of the U.S. National Science Foundation, the Collaborative Research Center (SFB 574) of the German Science Foundation, and the Central American science community. Over 120 scientists and students from 10 countries met in Costa Rica to synthesize this intense effort spanning from land to marine geological and geophysical studies.

A major topic of discussion at the meeting was the location of the seismogenic zone. The smectite to illite transformation is no longer a viable explanation for the onset of seismicity. Instead, laboratory measurements and theory point to fluid pressure and content as critical variables, and detailed seismic studies and mapping and sampling of fluid vent structures have led to a new hydrologic model for the erosional fore arc. Additionally, a change from high to low heat flow in the crust entering the Costa Rica trench coincides with a deepening in the onset of seismicity, suggesting that the shallow limit of earthquake generation is temperature-related.