In this study, we analyzed the ionospheric anomaly in the D region, which precedes the occurrence of earthquakes, by focusing on the VLF radio wave for navigation, which is used for military communication, among the observation data of the earth observation satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions). We analyzed the ionospheric anomaly in the D region that occurs prior to an earthquake. Next, based on the results, we propose the design of a 6U nano-satellite dedicated to the detection of earthquake precursory phenomena using navigational VLF radio waves: Prelude (Precursory electric field observation CubeSat demonstrator). The design of Prelude (Precursory electric field observation CubeSat demonstrator) is proposed.
In a previous study, the authors of Němec, Kamogawa et al. attributed this decrease in intensity to an increase in electron density in the D region. Kamogawa et al. attributed this decrease to an increase in electron density in the D region. Based on these results, our proposed satellite mission will be to observe ionospheric anomalies in the D-region that precede earthquakes for the purpose of short-term earthquake prediction in the future.
Němec et al. and Kamogawa et al. have studied the variation of electron density in the D region by analyzing the radio waves generated by lightning. However, the accuracy of this method is limited for the following three reasons: 1) the frequency of lightning is different depending on the season, 2) the frequency range of lightning is wider than that of thunderstorms, and 3) there are dispersion characteristics of radio waves due to ionospheric plasma. Therefore, in this study, we focused on the variation of electron density in the D region by focusing on the VLF charged wave for navigation, which has a constant frequency, continuous transmission, and temporal and spatial continuity. As a case study analysis, we confirmed the validity of the analysis of navigational VLF waves by focusing on the earthquake in southern Sumatra.
The results show that the navigational VLF signal intensity decreases significantly before the earthquake compared to the trajectories in the comparison counties. This suggests that the effects of ionospheric fluctuations shown by Němec In addition, we found that the VLF radio wave strength of Prelude was significantly reduced before the earthquake. Furthermore, this study showed the effectiveness of navigational VLF radio waves as a new analysis target for Prelude\u27s mission analysis. Therefore, we considered that there is a room to introduce a flexible system for the design and development of the science mission during the design and development of this satellite by using Systems Modeling
