11:00 AM - 1:00 PM
[SVC31-P03] Dense GNSS Observation of Mt. Usu by inexpensive and power-saving GNSS observation system
Keywords:GNSS observation, Mt. Usu
Geodetic observation of volcanoes is a powerful method for detecting pressure fluctuations in magma and hydrothermal systems and evaluating activity sequence and the imminence of eruptions. However, conventional GNSS instruments are expensive, and constructing a dense continuous observation network requires a lot of labor and cost. In recent years, with the development of GNSS positioning technology, inexpensive GNSS receivers and antennas have become popular, and by using them may be possible to construct a dense continuous observation network at a lower cost than before. In addition, observation stations near volcanoes are expected to be cut off from power during eruptions, so it is necessary to conduct long-term observations with a power-saving system.
Mt. Usu is an active volcano located in the southwestern part of Hokkaido, Japan. More than 20 years have passed since the eruption in 2000, and Murakami (in review) found ground deformation suggesting inflation of the deep source from the analysis of the GEONET F3 solution. In addition, the eruption of Usu occurred from various locations, and the estimation and prediction of eruption locations are essential issues. The dense GNSS observation network may contribute to estimating and predicting the eruption location.
In this study, we aim to construct a dense GNSS observation network around Mt. Usu and a real-time analysis process for continuous observation of the ground deformation before and after the next eruption and for estimation and prediction of the eruption location. In this presentation, we report on the inexpensive and power-saving GNSS observation system and the observation results of the first year.
The GNSS system constructed in this study costs about 100,000 yen per set. For the antennas, we used JIAXING JINCHANG ELECTRONIC TECHNOLOGY's JCA228E and Stoton's GGB0710, which are low-cost multi-band antennas (about 15,000 yen). We used u-blocks' ZED-F9P module (about 30,000 yen) for the GNSS receivers. RTKLIB 2.4.3 (Takasu et al., 2007) was installed on BiZright Technology's BH2, which is based on Raspberry Pi2 and has instantaneous power protection, to control the receiver and record data. It is powered by a 12V battery and consumes about 0.3 A.
We installed 16 new GNSS base points around Mt. Usu. Five GNSS observation systems were constructed, and 17 points, including one existing point, were observed for two weeks each from September 15 to November 11. The power source was a battery and solar panels. During the two weeks of surveying, BH2, the controller and data recorder, was rebooted several times, but the power was never lost, and the data were acquired continuously.
The data were converted to RINEX data using RTKLIB 2.4.3 and analyzed using two-frequency relative positioning with GEONET 950135 "Otaki" as the reference point. At the time of the observation, multi-GNSS data including GLONASS, Galileo, BeiDou, and QZSS were recorded, but here, the positioning calculation was performed only with GPS for the accuracy of the orbit information.
The positioning calculations showed that the standard deviation for one analysis was less than 1 mm in both the horizontal and vertical directions, and the standard deviation for two weeks was a few mm in the horizontal direction and about 1-2 cm in the vertical direction. Based on the experience, the ground deformation just prior to the eruption of Mt. Usu is on the order of several to several tens of meters and is expected to be adequately captured using the inexpensive GNSS observation systems.
In the future, we will continue to improve the continuity and telemetry of the newly established GNSS observation stations. In addition, we will construct a positioning calculation system using Real-Time Kinematic to enable quasi-real-time ground deformation observation and analysis. In addition, it is necessary to examine how much the newly established GNSS base points constrain the pressure fluctuation sources.
Mt. Usu is an active volcano located in the southwestern part of Hokkaido, Japan. More than 20 years have passed since the eruption in 2000, and Murakami (in review) found ground deformation suggesting inflation of the deep source from the analysis of the GEONET F3 solution. In addition, the eruption of Usu occurred from various locations, and the estimation and prediction of eruption locations are essential issues. The dense GNSS observation network may contribute to estimating and predicting the eruption location.
In this study, we aim to construct a dense GNSS observation network around Mt. Usu and a real-time analysis process for continuous observation of the ground deformation before and after the next eruption and for estimation and prediction of the eruption location. In this presentation, we report on the inexpensive and power-saving GNSS observation system and the observation results of the first year.
The GNSS system constructed in this study costs about 100,000 yen per set. For the antennas, we used JIAXING JINCHANG ELECTRONIC TECHNOLOGY's JCA228E and Stoton's GGB0710, which are low-cost multi-band antennas (about 15,000 yen). We used u-blocks' ZED-F9P module (about 30,000 yen) for the GNSS receivers. RTKLIB 2.4.3 (Takasu et al., 2007) was installed on BiZright Technology's BH2, which is based on Raspberry Pi2 and has instantaneous power protection, to control the receiver and record data. It is powered by a 12V battery and consumes about 0.3 A.
We installed 16 new GNSS base points around Mt. Usu. Five GNSS observation systems were constructed, and 17 points, including one existing point, were observed for two weeks each from September 15 to November 11. The power source was a battery and solar panels. During the two weeks of surveying, BH2, the controller and data recorder, was rebooted several times, but the power was never lost, and the data were acquired continuously.
The data were converted to RINEX data using RTKLIB 2.4.3 and analyzed using two-frequency relative positioning with GEONET 950135 "Otaki" as the reference point. At the time of the observation, multi-GNSS data including GLONASS, Galileo, BeiDou, and QZSS were recorded, but here, the positioning calculation was performed only with GPS for the accuracy of the orbit information.
The positioning calculations showed that the standard deviation for one analysis was less than 1 mm in both the horizontal and vertical directions, and the standard deviation for two weeks was a few mm in the horizontal direction and about 1-2 cm in the vertical direction. Based on the experience, the ground deformation just prior to the eruption of Mt. Usu is on the order of several to several tens of meters and is expected to be adequately captured using the inexpensive GNSS observation systems.
In the future, we will continue to improve the continuity and telemetry of the newly established GNSS observation stations. In addition, we will construct a positioning calculation system using Real-Time Kinematic to enable quasi-real-time ground deformation observation and analysis. In addition, it is necessary to examine how much the newly established GNSS base points constrain the pressure fluctuation sources.