Kinematic and Dynamic Models of Actively Deforming Lithosphere of the Western US

随着最近由Earthscope的PBO组件提供的美国西部GPS网络的扩展，地球动力学家准备在我们对岩石圈变形过程的理解上取得快速进展。作为贡献，我们正在开发新的方法来模拟岩石圈的变形，并将模型预测与GPS测量的地表运动进行比较。我们的方法是共同开发美国西部岩石圈变形的运动学和动力学模型，以解决一系列长期存在的问题，岩石圈如何变形，包括：1。美国西部的变形模式是什么？2.各种驱动力对岩石圈变形的相对影响是什么？3.什么是岩石圈的流变性？流变性如何随深度变化？4.岩石圈变形是自驱动的吗？5.沿断层沿着在哪里？还有，6。在何种程度上断层通过岩石圈中的弹性和粘性过程传递载荷而相互作用？我们正在开发长期和震间变形的运动学模型，这些模型将用于推断岩石圈的粘性结构、断层滑动速率、震间断层蠕动的分布和岩石圈块体运动。为此，我们正在构建三维地震周期模型，该模型由覆盖在层状粘性塑性层上的弹性地壳中的断层组成。我们正在研究在空间和时间的范围内，在地幔和地壳深部断层的震后弛豫过程可能是明显的GPS测量的震间变形和这些过程在多大程度上影响我们的估计断层滑动速率。我们也超越了纯粹的运动学模型，并发展长期岩石圈变形的薄板弹塑性模型，其中断层滑动响应于远场板块驱动力，由于重力势能的变化，和基底牵引力的内部体力。将这些长期运动预测与我们的震间变形模型和GPS观测相结合，我们试图推断各种驱动力对岩石圈变形的相对贡献。

With the recent expansion of the GPS network in the western US provided by the PBO component of Earthscope, geodynamicists are poised to make rapid progress in our understanding of the processes by which the lithosphere deforms.As a contribution, we are developing new methods for modeling the deformation of the lithosphere and comparing model predictions to GPS measurements of surface motions. Our approach is to jointly develop kinematic and dynamic models of lithosphere deformation in the western US to address a series of long-standing problems about how the lithosphere deforms including: 1. What is the mode of deformation in the western US? 2. What is the relative influence of various driving forces on lithosphere deformation? 3. What is the rheology of the lithosphere and how does rheology change with depth? 4. Is lithosphere deformation self-driving and decoupled from mantle flow? 5. Where is slip along faults aseismic and seismic? And, 6. To what extent do faults interact mechanically by transfer of loads through elastic and viscous processes in the lithosphere?We are developing kinematic models of long-term and interseismic deformation that will be used to infer the viscosity structure of the lithosphere, fault slip rates, distribution of interseismic fault creep, and lithospheric block motions. To do this we are constructing 3D earthquake cycle models consisting of faults in an elastic schizosphere overlying a layered viscous plastosphere. We are examining the extent in space and time to which postseismic relaxation processes in the mantle and on deep crustal faults might be evident in GPS measurements of interseismic deformation and to what extent these processes influence our estimates of fault slip rates. We are also moving beyond purely kinematic models and developing thin-plate elasto-plastic models of long-term lithosphere deformation in which faults slide in response to far-field plate driving forces, internal body forces due to variations in gravitational potential energy, and basal tractions. Combining these predictions of long-term motions with our interseismic deformation models and GPS observations, we are trying to infer the relative contributions of the various driving forces to lithosphere deformation.