The Geospatial Information Authority of Japan operates one of the largest GNSS Continuously Operating Reference Station networks in the world, GEONET, consisting of more than 1,300 GNSS-based control points in Japan. GEONET has become a social infrastructure for surveying and mapping, monitoring crustal deformation, and mitigating natural disasters. It is also used for precise positioning to guide construction and farm machines, and even for weather forecasting. Here we review its history and outlook, focusing on its application to disaster mitigation. As Japan is surrounded by four tectonic plates with interactions that lead to frequent earthquakes and volcanic activities, it must maintain such a geodetic infrastructure for monitoring crustal deformations in as near to real-time for possible disaster mitigation.

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