Developments in Geodetic Research Incorporating Seismological Elements

Abstract

　This article provides an overview of the author’s geodetic research activities since joining the Geodetic Society of Japan in 2011. The primary topics include postseismic processes, interseismic strain accumulation, slow slip events （SSEs）, earthquakes, and volcanic deformation. Highlights include the detection of Earth’s free oscillations using high-rate GNSS data following the 2011 Tohoku-Oki earthquake, and subsequent analyses of postseismic deformation due to afterslip and viscoelastic relaxation. Data-driven approaches using neural networks are also introduced. Interseismic deformation is examined through both block models and continuous strain rate fields, with applications to the Japanese archipelago. Regarding SSEs, research has focused on their spatiotemporal diversity and interactions with seismic and aseismic phenomena, particularly in the Nankai Trough, the Sagami Trough, and the Tonga Trench. The article further discusses stress changes, fluid effects, and ongoing debates on the definition of SSEs. In addition, it introduces studies on gravity-related modulation of seismicity and GNSS-based inverse modeling of volcanic inflation beneath Mt. Fuji. Throughout, the article highlights both the potential and limitations of GNSS for monitoring dynamic and long-term crustal deformation, offering a perspective on current geodetic methodologies and challenges.