Development of crust deformation monitor using GPS array data

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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.