Deforming Land and Earthquakes in Japan

The earth’s crust undulates dramatically across the Japanese archipelago and its surrounds, ranging from mountains of more than 3,000 meters to ocean trenches with depths exceeding 10,000 meters. This area is also a global hotspot for seismic activity, with around 20% of the world’s earthquakes occurring in and around Japan. The rugged topography and frequent earthquakes are attributable to the high degree of tectonic movement around the Japanese archipelago. Apart from the sudden and dramatic movement associated with earthquakes, tectonic movement proceeds extremely slowly and can only be detected using precise measurement technologies such as the global navigation satellite system (GNSS). GNSS is a system that allows users to track a precise location by receiving radio waves from satellites in space. A GNSS observation network in Japan was established some 30 years ago, enabling detailed insights into the movements of the four tectonic plates that intersect around the Japanese archipelago. Analysis of these movements has been instrumental to understanding the mechanisms of earthquake generation and forecasting their distribution.

This lecture will explain the relationship between earthquakes and the tectonic movements observed around the Japanese archipelago, using the 2024 M7.6 Noto Peninsula earthquake as an example.