We study the dynamically induced flexural topography in subduction numerical mechanical models. We focus on the topographic changes at the overriding plate (OP) surface induced by variations in OP kinematics, particularly when the subducting plate (SP) has a stationary motion after having reached the rigid base of the upper mantle. Our models consist of two viscoelastic plates with free surfaces and an isoviscous mantle. Friction is imposed along the planar subduction interface. We first characterize the main topographic features at a constant OP velocity, using spatial definitions based on geometrical estimations of the volcanic arc position. The models exhibit the formation of a bulge in the forearc area followed landwards by a depression and a smaller second bulge, both bracketing the arc region. The steady‐state distance to the trench of these features increases with OP velocity. Their amplitude is affected by the far‐field OP tectonic regime that depends on kinematics, and plates and subduction interface strength. We next test the effect of sudden changes in OP velocity. An OP acceleration yields a transient topographic tilt, during which the outer forearc quickly subsides whereas the arc region uplifts, and that is followed by reverse slower motions. An OP slowdown induces opposite motions. The rates of elevation change during the tilt are approximately proportional to velocity variations and mainly sensitive to the SP strength. The rates are higher than 0.1 mm/yr for velocity changes higher than 1 cm/yr. We suggest that topographic accommodations of OP velocity changes should be considered when quantifying nonisostatic topography.

中文翻译：

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俯冲带二维模型中表面形貌的覆盖板速度控制

我们在俯冲数值力学模型中研究了动态诱发的弯曲形貌。我们关注由OP运动学变化引起的上覆板（OP）表面的形貌变化，尤其是当俯冲板（SP）到达上地幔的刚性基底后发生静止运动时。我们的模型包括两个具有自由表面的粘弹性板和一个等粘度的地幔。沿平面俯冲界面施加摩擦。我们首先使用基于火山弧位置的几何估计的空间定义，以恒定的OP速度表征主要地形特征。这些模型显示出在前臂区域形成了一个凸起，然后向内陆着凹陷和较小的第二个凸起，两者都包围了弧形区域。这些特征到沟槽的稳态距离随着OP速度的增加而增加。它们的振幅受远场OP构造机制的影响，后者取决于运动学，板块和俯冲界面强度。接下来，我们测试OP速度突然变化的影响。OP加速度会产生瞬时的地形倾斜，在此期间外前臂快速消退，而弧形区域抬高，然后反向缓慢运动。OP减速会引起相反的运动。倾斜期间的海拔变化率与速度变化大致成比例，并且主要对SP强度敏感。当速度变化高于1 cm / yr时，速率高于0.1 mm / yr。我们建议在量化非等静态地形时应考虑OP速度变化的地形适应性。