IODP³ Expedition 502 will drill the outer-rise area of the Japan Trench, where the sediments above the acoustic basement are thin. The thin sediments are hypothesized to be caused by basalt intrusions or lava flows related to petit-spot magmatism, a type of volcanic activity caused by the bending of the incoming plate near the trench. Our goal is to determine whether petit-spot magmatism is more widespread than previously thought and to understand its role in the Earth's systems.