Definition of underthrust in English:



[with object]Geology
  • 1Force (a crustal plate or other body of rock) beneath another formation.

    ‘the Farallon plate was being underthrust beneath the North American plate’
    ‘this sediment may be deformed by the underthrusting’
    • ‘Patterns of this type can be readily explained by accretionary tectonism, whereby a packet of sediment accreted at the toe of the prism is underthrust and buried beneath an overburden of older strata.’
    • ‘Here the Papua New Guinea continental crust appears to be underthrusting the adjacent marginal basin and obduction of the ophiolite is occurring in an uphill direction.’
    • ‘The tensional stresses in the uplift can be relaxed by, for example, underthrusting in a subduction zone, or contraction in surrounding regions.’
    1. 1.1 Be forced underneath (another formation)
      ‘plate X is underthrusting plate Y in a NE direction’


  • An instance of one crustal plate or other body of rock being forced underneath another.

    ‘the westward underthrust of the Pacific Ocean plate’
    • ‘We suggest that because the upper portion of underthrust sections lacked any thick, water-saturated clastic deposits this did not favour the formation of melanges.’