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Subduction dynamics as revealed by trench migration
Author(s) -
Lallemand Serge,
Heuret Arnauld,
Faccenna Claudio,
Funiciello Francesca
Publication year - 2008
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2007tc002212
Subject(s) - trench , subduction , geology , slab , kinematics , deformation (meteorology) , seismology , tectonics , geophysics , materials science , physics , composite material , oceanography , layer (electronics) , classical mechanics
New estimates of trench migration rates allow us to address the dynamics of trench migration and back‐arc strain. We show that trench migration is primarily controlled by the subducting plate velocity V sub , which largely depends on its age at the trench. Using the hot and weak arc to back‐arc region as a strain sensor, we define neutral arcs characterized by the absence of significant strain, meaning places where the forces (slab pull, bending, and anchoring) almost balance along the interface between the plates. We show that neutral subduction zones satisfy the kinematic relation between trench and subducting plate absolute motions: V t = 0.5 V sub − 2.3 (in cm a −1 ) in the HS3 reference frame. Deformation occurs when the velocity combination deviates from kinematic equilibrium. Balancing the torque components of the forces acting at the trench indicates that stiff (old) subducting plates facilitate trench advance by resisting bending.