Tectonic


Tectonic environment in Nicaragua, is constituted mainly by two plates which interacted constantly, and are the source of the principal part of quakes registered in the country.The plates which interactues are the Coco and Caribbean plate, the first subduce the Caribbean plate. (See figure 1). Reciently in 2000 year was shown in a report, some characteristics of the structure crust in the Pacific coast. Nicaragua´s thie test was realize taking data of p waves from seismic refraction (wide angle), also from existent data of reflection, borehole and gravity. In agreement to the investigators the oceanic crust of Coco´s plate have a thickness of 5.5 km and this cover with a skinny layer of sediments, the inferior side of this plate its identify at 40 km deep. This position, it agree with searches, that was made before through the national seismic network. Under this, was found other structure with velocities from 3.5 km/s at 5.2km/s, this occurs insite, where the continental shelf start to bend, it is estimated that this have a thickness of 15 km. and a wide of 80 km. Which it extends from the margin of plate, until aproximately the half of oceanic crust, upper to this structure was found a part that shown velocities from 6.0 km/s and have a thickness of 10 km. The analysis of gravity forces showed that the density of the upper structure is in a range of 2.6 to 2.7gr/cm3, while the lower structure,from the velocities and densities data, of this material was concluded that piece of cloak is constituted of ophiolitics rocks, which is finished 50 km, before coast, near of coast the plinth in Sandino basin it is conformed for igneous rocks older, it was found through boreholes, under of sedimentary rocks from superior cretaceous in Nicaragua land. Under plinth ophiolitic was found splinters with velocities typical for materials of the mantle in deeps from 12 to 18 km, thing that concords with boundaries slope between the seismogenetic zone .

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