A Steep Slab at the Yap Trench Resulted from Subducting Oceanic Plateaus

Abstract Interaction of oceanic plateaus with trenches plays a vital role in subduction activities and tectonic evolutions. The Yap trench is a rare case of an oceanic plateau subduction system. However, the knowledge of the impacts of plateau-trench interaction on subduction activity is still insufficient, due to a lack of seismological observations. Using ocean-bottom seismometer data near the Yap trench from April 2016 to May 2017, we conduct seismicity analyses in the Yap subduction zone by utilizing a machine-learning algorithm and matched-filter detections. The pattern of seismicity in the Yap trench exhibits characteristics similar to typical active subduction zones. The seismicity delineates a steep subducting slab, which may have resulted from the blocking of the buoyant Caroline Plateau. The majority of earthquakes are shallower than 80 km in the event-detectable area in the Yap trench, much shallower than the potential slab depth of 350 km from the previous seismic tomography images.