North America Dynamics and Western U. S. Deformation

EAR-0106892 Eugene D.Humphreas研究人员通过对施加在板块上的力进行建模，并将预测的应力与正在进行的构造样式和在钻孔中观察到的应力进行比较，来解决北美板块的动力学问题。采用有限元方法进行建模。施加到模拟北美的输入力包括边界力和基准力，以及板块内部产生的力(由势能变化引起，如地形产生的)。施加的力的相对大小被估计以考虑应力和变形信息。此外，由于北美施加的许多力的大小都是先验的(如山脊推进)，所有施加的力的大小将受到很好的限制。构造应力使北美变形的速度与其强度成反比。研究人员用粘性流变学对强度进行建模，他们通过计算出的应力与(众所周知的)应变率之比来估计强度。研究可分为几个任务：估计输入场，描述北美适当的有限元表示，评估模型预测与可观测数据，以及随着建模的进展，分解输入场并评估其唯一性。

EAR-0106892Eugene D. HumphreysThe investigators address North America plate dynamics by modeling the forces applied to theplate and comparing the predicted stresses with those inferred from the styleof ongoing tectonics and those observed in drill holes. Modeling is done withthe finite element method. Input forces applied to modeled North Americainclude boundary and basal forces, and those generated internal to the plate(arising from potential energy variations such as those created by topography).The relative magnitudes of applied forces are estimated to account for stressand deformation information. Furthermore, because the magnitude of many of theforces applied North America are well known a priori (such as ridge push), themagnitude of all the the applied forces will be well constrained. Tectonicstresses deform North America at a rate inversely proportional to its strength.The investigators model strength with a viscous rheology, which they estimate by ratioing thecalculated stress with the (reasonably well known) strain rate.The research can be divided into several tasks: estimation of input fields,description of an appropriate finite element representation of North America,evaluation of model predictions against observables, and as modeling progressestoward resolving the input fields and assessment of their uniqueness.--