摘要：Plate tectonics is taken as one of the four major breakthroughs in natural sciences in the 20th century, sittingalongside the theory of relativity, quantum mechanics andmolecular biology. But, after 50 years of intensive study, twofundamental questions remain unsolved: What is the maindriving force of plate tectonics, and, how did plate tectonicsget started? Both of these questions are related to the initiationof subduction, which is a more difficult issue to constrain thanan initiation of plate spreading (McKenzie, 1977). There arecurrently two competing models for the initiation of platesubduction, spontaneous and induced (Stern, 2004).
