Why do earthquakes occur near the Okinawa Trough and the Ryukyu Island arc?

Earthquakes occur near the Okinawa Trough and the Ryukyu Island arc primarily due to the complex tectonic activity in the region, where the Philippine Plate is subducting beneath the Eurasian Plate.1

This process of subduction—where one tectonic plate sinks into the Earth's interior beneath another—creates significant stress and geological instability. The Ryukyu Island arc is a product of this convergent boundary, and the associated volcanism and faulting contribute to frequent seismic events.2134

Furthermore, the Okinawa Trough is a relatively young marginal basin, approximately 10 million years old, formed by crustal extension. The combination of this ongoing extensional tectonics, the presence of active volcanoes, and the convergence of major crustal plates results in the concentration of earthquake epicentres along the axis of the trough and the island arc.341