Collaborative Research: Mechanisms of Postseismic Deformation Following the 2002 Denali Fault Earthquake Sequence

合作研究：2002年德纳里断层地震序列之后的震后变形机制2002年11月3日发生的MW 7.9德纳里地震创造了收集地表变形测量结果的机会，这些测量结果需要在我们对地球岩石圈主要变形机制和断层带及周围地壳和上地幔流变参数的认识方面取得重大进展。德纳里地震的大力矩、精确的震前形变场和即时的现场响应使其成为现代空间大地测量方法出现以来解决震后形变问题的最有希望的目标。我们的观测策略包括在距离破裂范围很广的16个地点进行连续GPS（CGPS）测量，包括一些在150公里处，以区分深断裂带、下地壳和上地幔的作用。其中11个网站在事件发生后两周内安装完毕，并一直在持续运行。所提出的研究的一个基本目标是精确地确定震后变形信号的时间依赖性。将利用现有基准，每年进行两次全球定位系统活动，作为对CGPS测量的补充，以便在空间上增加震后位移场的密度。我们还将测试干涉合成孔径雷达测量同震和震后早期形变的能力。观测工作将通过综合模拟工作来补充，以评估候选形变机制，如速度加强后滑、孔隙弹性反弹和下地壳和上地幔的粘性流动。表征这些机制中的每一个的相对重要性是本研究项目的主要目标。我们将充分探索不同模型类型的能力（例如，断裂上和断裂下的随时间变化的后滑与下地壳和上地幔中的幂律流动），以拟合数据，同时与互补的地质和地球物理约束相一致。PI：J. Freymueller（阿拉斯加大学，费尔班克斯），R. Burgmann（UC Berkeley），E.加莱（普渡大学）

Collaborative Research: Mechanisms of Postseismic Deformation Following the 2002 Denali Fault Earthquake SequenceThe occurrence of the Mw 7.9 November 3, 2002 Denali earthquake has created the opportunity to collect the surface deformation measurements needed to make significant improvements in our knowledge of the dominant deformation mechanisms in the Earth's lithosphere and the rheological parameters of the fault zone and surrounding crust and upper mantle. The large moment of the Denali earthquake, the precise pre-earthquake deformation field, and the immediate field response make this the most promising target to address postseismic deformation problems since modern space-geodetic methods became available.Our observational strategy consists of continuous GPS (CGPS) measurements at 16 sites located at a wide range of distances from the rupture, including some at 150 km, in order to distinguish processes in the deep fault zone, the lower crust and upper mantle. Eleven of these sites were installed within two weeks after the event and have since been operating continuously. A fundamental objective of the proposed research is to precisely determine the time-dependence of the postseismic deformation signal. CGPS measurements will be complemented by two GPS campaigns per year, using existing benchmarks, in order to spatially densify the postseismic displacement field. We will also test the ability of InSAR to measure the coseismic and early postseismic deformation.The observational efforts will be complemented by comprehensive modeling efforts to evaluate candidate deformation mechanisms such as velocity-strengthening afterslip, poroelastic rebound, and viscous flow in the lower crust and upper mantle. Characterization of the relative importance of each of these mechanisms is a major goal of this research project. We will fully explore the ability of the different model types (e.g., time-dependent afterslip on and below the rupture vs. powerlaw flow in the lower crust and upper mantle) to fit the data while being consistent with complementary geological and geophysical constraints. PIs: J. Freymueller (Univ. Alaska, Fairbanks), R. Burgmann (UC Berkeley), E. Calais (Purdue University)