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Associated with the slab suction force is the idea of trench roll-back. As a slab of oceanic crust subducts into the mantle, the hinge of the plate (the point where the plate begins to subduct) tends to regress away from the trench. This occurs because there is effectively no force to hold the hinge in one location. [5]
Trench suction is included in this causal mechanism. Trench suction is induced by the flow of the asthenosphere in the mantle wedge area; trench suction increases with subduction velocity, a decrease of the mantle wedge thickness, or an increase in the mantle wedge viscosity. [13]
The backward motion of the subduction zone relative to the motion of the plate which is being subducted is called trench rollback (also known as hinge rollback or hinge retreat). As the subduction zone and its associated trench pull backward, the overriding plate is stretched, thinning the crust and forming a back-arc basin.
The arc-trench complex is the surface expression of a much deeper structure. Though not directly accessible, the deeper portions can be studied using geophysics and geochemistry . Subduction zones are defined by an inclined zone of earthquakes , the Wadati–Benioff zone , that dips away from the trench and extends down below the volcanic arc ...
The central Chile segment of the trench is moderately sedimented, with sediments onlapping onto pelagic sediments or ocean basement of the subducting slab, but the trench morphology is still clearly discernible. The southern Chile segment of the trench is fully sedimented, to the point where the outer rise and slope are no longer discernible.
A suction excavator, or vacuum excavator, is a construction vehicle that removes heavy debris or other materials from a hole on land using vacuuming. Suction excavators are meant to be less destructive than regular excavators . [ 1 ]
This can be done in a number of ways, notably with a ′′cutter-suction′′ system, with the use of buckets or with a backhoe. [36] ″A buried pipe is far better protected than a pipe in an open trench.″ [41] This is commonly done either by covering the structure with rocks quarried from a nearby shoreline. Alternatively, the soil ...
Slab pull is a geophysical mechanism whereby the cooling and subsequent densifying of a subducting tectonic plate produces a downward force along the rest of the plate. In 1975 Forsyth and Uyeda used the inverse theory method to show that, of the many forces likely to be driving plate motion, slab pull was the strongest. [1]