Subduction

Subduction (pronounced sub-duhk-shuhn)

(1) The action of being pushed or drawn beneath another object.

(1) An act or instance of subducting; subtraction or withdrawal; an act of taking away.

(2) In geology, the process by which collision of the earth's crustal plates results in one lithospheric plate being drawn down or overridden by another, localized along the juncture (subduction zone) of two plates, sometimes resulting in tensions and faulting in the earth's crust, with earthquakes and volcanic eruptions

(3) In specialized us in applied optics, the act of turning the eye downwards.

(4) In mathematics, a surjection between diffeological spaces such that the target is identified as the push-forward of the source.

1570-1580: From the Latin subductiōn (nominative subductiō) (pulling up, computation).  The original sense was “withdrawal, removal; the action of taking away” (originally of noxious substances from the body), from the Latin subductiōnem (nominative subductiō) (a withdrawal, drawing up, hauling ashore), a noun of action from the past participle stem of subducere (to draw away, take away).  From the 1660s it was used in the sense of “an act of subduing; fact of being subdued” while the now familiar geological sense, referring to the edge of a tectonic plate dipping under a neighboring plate came into use in English only by 1970, following the adoption in French in 1951.  The word is now peculiar to geology, the newness a consequence of plate tectonics becoming well understood only from the mid 1960s.  The verb subduct (used first in the 1570s in the sense of “subtract”) was from subductus, past participle of subducere, and the geological sense is from 1971, a back-formation from the noun subduction.  Subduction is a noun, subduct, subducting & subducted are verbs, subductively is an adverb and subductive is an adjective; the noun plural is subductions.

Subduction is a geological process which happens where the boundaries of tectonic plates converge and one plate moves under another, being forced or, under the force of gravity, sinking into the mantle. Regions where this process occurs are known as subduction zones and rates of subduction are usually small, averaging one to three inches (25-75mm) per year.

Affected plates include both oceanic and continental crusts.   Dutch scientists Douwe van der Meer, Douwe van Hinsbergen, and Wim Spakman of Utrecht University published Atlas of the Underworld in the journal Tectonophysics documenting ninety-four distinct slabs.