Development of crust deformation monitor using GPS array data

本研究旨在开发一种地壳变形监测仪，通过分析全国范围内的GPS阵列，连续监测日本岛屿的状态。该监测仪的关键是利用在一个离散点上测量的数据和应力满足的平衡方程来预测应力场的逆分析理论。通过对实测应变和预测应力的比较，可以对材料的力学状态进行评价，识别材料的表观力学性能。通过应力应变均已知的数值实验，验证了地壳变形监测的有效性。结果表明，随着数据质量和数量的增加，监测系统能够发现目标的应力和状态，并对监测变量的不确定性进行估计。应用该监测仪对1998 ~ 2002年全国GPS数据的实际数据进行了分析。鉴于现有数据的质量，监测仪试图确定泊松比在日本群岛上的分布，这与通过人工地震测量确定的s波和p波结构是一致的。这说明了已开发的地壳变形监测仪的实用性，但随着实测数据量的增加，还需要进一步的修改和完善，这样的修改可以更加合理。为了估计监测场变量的不确定性，提出了一种新的连续介质力学随机建模理论。该理论已应用于地壳变形监测。

This research is aimed at developing a crust deformation monitor which continuously monitors the state of the Japanese Island by analyzing the nation-wide array of GPS. The key point of the monitor is the inverse analysis theory that predict a stress field by using data measured in a discrete and the equilibrium equation that stress satisfies. By comparing the measured strain and the predicted stress, the monitor is able to evaluate the mechanical state for instance, apparent mechanical properties are identified. The validity of the crust deformation monitor has been checked through a numerical experiment in which both stress and strain are known. It is shown that as the quality and quantity of the data increases, the monitor is able to find the stress and state of the target the uncertainty of the monitored variables is estimated. The monitor is applied to analyze actual data of the nation-wide GPS data during 1998-2002. In view of the quality of available data, the monitor seeks to identify the distribution of Poisson's ratio over the Japanese Islands, which is in harmony with the S-wave and P-wave structure which is identified through the artificial earthquake measurement. This shows the usefulness of the developed crust deformation monitor, although further modification and improvement is needed as the quantity of the measured data increase such modification can be more rationally made. In order to estimate the uncertainty of the monitored field variables, a new theory of stochastic modeling has been developed for continuum mechanics. The theory is being applied to the crust deformation monitor.