2005 Interior of the Earth Gordon Conference

2005年地球内部戈登会议

• 批准号: 0531095
• 负责人: Lars Stixrude
• 金额: $ 2.35万
• 依托单位: Gordon Research Conferences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0531095&HistoricalAwards=false
• 关键词: 2005; Interior; Earth; Gordon; Conference

The actual physical process of an earthquake-the propagating fracture that breaks the friction holding two sides of the fault together allowing them to slip past one another-is never directly observed. It must be inferred by analysis of the elastic waves and the deformation that the earthquake caused. The data from the MW 6.0 Parkfield earthquake of September 28, 2004, provide an unprecedented opportunity to infer the dynamics of an earthquake source. Within 20 km of the fault, there are 56 three-component strong motion accelerographs, a dense 13-element array (UPSAR), 13 continuous GPS sites with 10 or more GPS campaign sites and four borehole dilatometers. These data can be inverted to find the kinematic description of the earthquake source. The kinematic description lays the foundation for describing the nonlinear process of earthquake dynamics. The mechanics of inverting data have become routine, but the scientific questions that the Parkfield data can answer go beyond simply finding a kinematic faulting model. Inverting all of the data to find a "best" model of the faulting process will be done, but this data set provides a much greater opportunity. The richness of the data allows a multifaceted approach to inverting the data. Most importantly, the density and quality of the data allow a rare opportunity to explore what features of the kinematic models are robust and well resolved. The kinematic features that are robust will define features of the earthquake that will be vital for establishing the best initial stress conditions for developing dynamical models that will simulate the propagating fracture. There are many fundamental questions that will be addressed. Why did the 2004 rupture go from southeast to northwest, opposite to that of the 1934 and 1966 earthquakes? With minor perturbations to the initial stress conditions could the rupture have nucleated near Middle Mountain and propagated to the southeast? Even though the rupture is primarily northwest, what caused the large ground motions to the southeast? Do they arise from dynamics of the rupture front? It has been proposed that maps of b-values on the fault correlate with regions of high and low stress on the fault. The 2004 mainshock hypocenter is within a region of high stress. Will the dynamic rupture follow a path that mimics the b-value maps? What will dynamic models give for stress changes on different parts of the fault? Will the variation be as large as that found in studies of prior seismicity. The answers depend on dynamics of the rupture. By inverting the abundant Parkfield data, a kinematic model is deduced that will provide the initial conditions for dynamic simulations, which in turn will allow one of the most detailed examinations of the dynamics of an earthquake.

地震的实际物理过程 - 传播裂缝打破了摩擦的两侧，使它们彼此彼此滑落，从未直接观察到它们。必须通过分析弹性波和地震引起的变形来推断。 2004年9月28日的MW 6.0 Parkfield地震的数据为推断地震来源的动态提供了前所未有的机会。故障20公里以内，有56个三组分的强运动加速器，一个密集的13个元素阵列（UPSAR），13个连续的GPS站点，具有10个或更多GPS运动站点和4个钻孔扩张仪。这些数据可以倒置以找到地震来源的运动学描述。运动学描述为描述地震动力学的非线性过程奠定了基础。颠倒数据的机制已成为常规，但是Parkfield数据可以回答的科学问题不仅仅是找到运动学故障模型。将完成所有数据以找到故障过程的“最佳”模型，但是该数据集为其提供了更大的机会。数据的丰富性允许采用多方面的方法来反转数据。最重要的是，数据的密度和质量允许难得的机会探索运动学模型的哪些特征是强大且已解决的。强大的运动学特征将定义地震的特征，这对于建立最佳初始应力条件至关重要，以开发将模拟传播裂缝的动力学模型。 将要解决许多基本问题。为什么2004年的破裂从东南到西北，与1934年和1966年的地震相对？由于对初始应力条件的扰动较小，破裂是否可以在中山附近成核并传播到东南？即使破裂主要是西北，是什么导致向东南的大型地面运动？它们是由破裂阵线的动态引起的吗？已经提出，断层上B值的地图与断层高应力和低应力区域相关。 2004年主震次中心位于高应力的区域内。动态破裂会遵循模仿B值地图的路径吗？动态模型将使故障不同部分的压力变化给什么变化？变异会像先前的地震性研究中所发现的那样大。答案取决于破裂的动力。通过颠倒丰富的Parkfield数据，推导了运动模型，该模型将为动态模拟提供初始条件，这又将允许对地震动力学的最详细检查之一。