La relación entre tectónica, flujo de fluidos y la formación de terremotos en el margen convergente de Centro América

• Autores: C. R. Ranero, I. Grevemeyer, W. Weinrebe
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 6, 3, 2004 (Ejemplar dedicado a: IV Congreso Geológico de España (Zaragoza, 12-15 julio, 2004)), págs. 97-100
• Idioma: español
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• Resumen

  • Seismic reflection images, multibeam bathymetry, heat flux measurements and microearthquakes show the relationship between tectonic processes, fluid flow and seismogenesis at the Middle America Margin dominated by tectonic erosion of the continental plate. The continental plate is structured in areas showing different deformation. The shelf is underlain by a coherent basement and little deformed sediment. Beneath the upper slope large faults cut the basement and sediment cover, but a well-developed canyon system indicates relative stability. The middle slope shows a tectonically disrupted structure. Canyons stop downslope at the middle slope cut by numerous faults, and associated mud diapirs with chemosynthetic fauna. The faults cut the upper plate tapping fluids from the plate boundary. The lower slope is a thin apex of a little coherent overriding plate. The seafloor shows pervasive faulting and dismembered blocks ride over horsts and grabens of the subducting plate mimicking their topography. Beneath the middle to upper slope, temperatures at the plate boundary increase from ~60°C to ~150°C. Thus, early dehydration reactions of subducted sediment occur there, where hydrofracturing and upper plate erosion is fastest. Seismic rupture, indicated by microearthquakes, extends into the I00°-150°C transition. Large earthquakes nucleate where fluids have been largely exhausted.