The objective of this study is to clarify the state changes of the Earth's crust, specifically focusing on periods without earthquakes and volcanic activities by analyzing the continuous seismic waveforms. My primary goal is to estimate the variations in model parameters associated with environmental factors that influence the crustal structure, utilizing the data assimilation method. It has been observed that the velocity of seismic waves propagating in the crust are constantly changing due to environmental changes such as changes in groundwater level and temperature. However, previous studies have only accumulated results for a limited number of locations, and the crustal response to environmental changes over a wide range of spatial scales remain unclear. In this study, I quantify the changes in the crustal state in response to various environmental changes and map the model parameters from a few meters to several tens of kilometers resolution. If we know the "normal" state of the crust, we expect to be able to estimate the state changes during earthquakes and volcanic eruptions more precisely. This project also aims to apply seismic wave analysis to fields other than seismology, because it enables remote monitoring of environmental changes in places that cannot be directly observed.