Monitoring of Japanese ground displacement following environmental, tectonic or seismic events
This dataset provides daily position time series (North, East and Vertical), in the ITRF14 reference frame [Altamimi et al., 2017], processed at ISTerre for all the stations from the GNSS Earth Observation Network System (GEONET) in Japan [Tsuji et al., 2017].
Global Navigation Satellite System (GNSS) is one of the reference sources of information in geodesy. Geodetic data can help analyze the ground displacement with millimeter precision as well as monitoring its evolution through time (Blewitt et al., 2018). As Japan undergoes a lot of surface deformations and is under the threat of several telluric hazards (earthquakes, tsunamis or volcanic eruptions), the Geospatial Information Authority of Japan (GSI) started to install GEONET in 1994. The network is nowadays made of 1439 GNSS stations at a distance of ∼20 km from each other.
The data from GEONET have been processed by different groups to transform the raw GNSS observation into position time series that are more easily interpretable. The GEONET F3 solution made available by the Japan Meteorological Agency [Nakagawa et al., 2009; Tsuji et al., 2017] and the Nevada Geodetic Laboratory (NGL) solutions (http://geodesy.unr.edu) [Blewitt et al., 2018] for data more recent than 2008, have notably been used in a number of studies of geophysical events, among which the great 2011 Tohoku earthquake [e.g. Hooper et al., 2013; Sun et al., 2014]. We provide an important independent solution that allows for benchmarking and refined studies. The daily position time series were calculated with GAMIT software [Herring et al., 2018] that uses a double difference approach and that estimates the station positions, the atmospheric delays, the satellite orbits, and the Earth orientation parameters.
Such position time series are commonly used to monitor the ground displacement as a response to environmental (e.g. tides, snow pack or hydrology), tectonic or seismic forcing, and to characterize the mechanical response of the earth to these forcings. If one considers only the research field dealing with the seismic cycle, major advances could be made using the GEONET data, such as the discovery of post-seismic deformation following subduction earthquakes [Heki et al., 1997], or the discovery of Episodic Tremor and Slip (ETS) in Nankai [Obara et al., 2004] that constituted a paradigm shift in the understanding of fault mechanics and earthquake physics.
The current data set was used in the frame of 4 PhD theses, and allowed to: revisit the recurrence of Slow Slip Event in Boso [Gardonio et al., 2018]; characterize the change in coupling offshore Honshu before the 2011 Tohoku earthquake (Marill et al., 2021); show that the post-seismic deformation following Tohoku follows a brittle creep law (Periollat et al., 2022), look for small slow slip events offshore Honshu (Marill et al., 2022); and develop machine learning methods to characterize the source of earthquakes using GNSS (Costantino et al. 2022).
Figure (a): Japan tectonic context and deployment of GEONET. Each color point represents one station and its color the year of its installation. The triangles are the stations for which time series are shown in the right panel.
Figure (b): Comparison of the GAMIT/GLOBK processed at ISTerre and F3 from JMA. The name of the stations are given at the beginning of each time series and their location is shown in Figure 2.2. Detrended time series for the East component are shown: blue for GAMIT/GLOBK, black for F3. The black vertical line shows to the occurrence time of the 2011 Mw 9.0 Tohoku earthquake. For visualisation purpose, the co-seismic offset generated by the 2011 Mw 9.0 Tohoku earthquake was removed.