Examinando por Autor "Gonzalez, JL"

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    Coastal erosion and village relocation: A Colombian case study
    (ELSEVIER SCI LTD, 2000-01-01) Correa, ID; Gonzalez, JL; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
    Because of its tectonic setting, the Pacific coast of Colombia is subject to a variety of geological hazards, including earthquakes, tsunamis and associated phenomena such as regional and local coastal subsidence, flooding and soil liquefaction. Erosional trends are prevalent along much of the 700 km long, low barrier island's shorelines of the Pacific littoral and land losses are enhanced by factors such as 30 cm regional sea level rises associated to the occurrence of El Nino. Marine erosion is threatening more seashore littoral villages and worsening the already difficult socioeconomic conditions of most part of the inhabitants. Because of diverse and strong motivations to stay near the sea, the responses of barriers island's inhabitants to marine erosion has consisted in most cases of repetitive in-shore and along-shore directed relocations of villages, rather than definitive abandonment of the islands. In the long run, this procedure only has postponed the problem and led to repetitive relocations and economical losses. The recent inland relocation of El Choncho village, on the San Juan River delta, illustrates a different response to marine erosion. Although a new along-shore relocation was physically possible, inhabitants decided to abandon the barrier island and migrate to an interior, ancient beach ridge complex, applying a prudent solution which will be the most appropriate for other threatened villages of the Pacific littoral. A detailed geomorphologic mapping program must be conducted in order to identify appropriate sites for inland relocation of existing villages on the barriers islands of the Colombian Pacific coast. (C) 2000 Elsevier Science Ltd.Because of its tectonic setting, the Pacific coast of Colombia is subject to a variety of geological hazards, including earthquakes, tsunamis and associated phenomena such as regional and local coastal subsidence, flooding and soil liquefaction. Erosional trends are prevalent along much of the 700 km long, low barrier island's shorelines of the Pacific littoral and land losses are enhanced by factors such as 30 cm regional sea level rises associated to the occurrence of El Nino. Marine erosion is threatening more seashore littoral villages and worsening the already difficult socioeconomic conditions of most part of the inhabitants. Because of diverse and strong motivations to stay near the sea, the responses of barriers island's inhabitants to marine erosion has consisted in most cases of repetitive in-shore and along-shore directed relocations of villages, rather than definitive abandonment of the islands. In the long run, this procedure only has postponed the problem and led to repetitive relocations and economical losses. The recent inland relocation of El Choncho village, on the San Juan River delta, illustrates a different response to marine erosion. Although a new along-shore relocation was physically possible, inhabitants decided to abandon the barrier island and migrate to an interior, ancient beach ridge complex, applying a prudent solution which will be the most appropriate for other threatened villages of the Pacific littoral. A detailed geomorphologic mapping program must be conducted in order to identify appropriate sites for inland relocation of existing villages on the barriers islands of the Colombian Pacific coast.
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    Frequent non-storm washover of barrier islands, Pacific coast of Colombia
    (COASTAL EDUCATION & RESEARCH FOUNDATION, 2000-01-01) Morton, RA; Gonzalez, JL; Lopez, GI; Correa, ID; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
    Barrier islands of the Pacific coast of Colombia repeatedly experience severe washover even when breaking waves in the eastern Pacific are low and onshore winds are calm. On the barrier island of El Choncho, recent non-storm washover events have breached a new inlet, caused rapid beach retreat, destroyed a shoreline protection structure, and flooded a small village of indigenous people so frequently that it had to be relocated. Barrier washover may be augmented by lowered land elevations associated with earthquake-induced subsidence or long-term beach retreat, but temporally it is most closely associated with a 20 to 30 cm regional increase in sea level caused by El Nino. The contradiction of a tranquil tropical island scene simultaneously disturbed by hostile turbulent washover may be unique at present, but it exemplifies how coastal plains throughout the world would be affected if sea level were to rise rapidly as a result of global warming.
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    Late Holocene evidence of coseismic subsidence on the San Juan delta, Pacific coast of Colombia
    (COASTAL EDUCATION & RESEARCH FOUNDATION, 2001-01-01) Gonzalez, JL; Correa, ID; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
    The San Juan delta of Colombia formed under a complex physical setting. Among the unusual factors that controlled the delta formation are: its location in an area with one of the highest precipitation rate anywhere in the world, highly variable river discharge and high sea levels of short duration, both associated with El Niño-La Niña climatic disturbance, and high mesotidal range combined with a medium to low wave energy. Of all the aspects that make the physical setting complex, the high seismicity produced by the subduction of the Nazca plate under the South American plate, has perhaps, been the most important controlling factor in the Late Holocene development of the delta. Coring on its SW island retrieved soils buried, 1.2-1.5 m by intertidal deposits; the sharp contact between the soils and the mantling deposits, implies large sudden submergence, which is most simply explained as being coseismic, associated with the high seismicity of the area. Timing of the earthquake that caused subsidence, is placed around 500 years BP. Evidence from recent earthquakes along the South central Pacific coast of Colombia indicates that - subsidence > 1 m requires a M 7.9 or greater earthquake.