Seismic line MX-16 transects the Middle America Trench on the Pacific coast of Mexico. The bathymetric map reveals a narrow continental shelf, a steep trench slope, and an axial trench about 5 km below sea level. A large submarine canyon cuts the upper slope in the vicinity of line MX-16. This area was extensively drilled during Leg 66 of the Deep Sea Drilling Project (Watkins et al., 1982).

Subduction in the area has been active intermittently during the last 100 m.y. (Karig et al., 1978). The convergence rate of the underthrusting Cocos plate relative to the overriding North American plate is inferred to be about 7 cm/yr (Minster and Jordan, 1978). Leg 66 drilling results suggest the continental margin in the area was truncated between 10 and 35 m.y.B.P., perhaps by transcurrent faulting or subduction erosion (Moore et al., 1982). A small accreted wedge subsequently developed by sediment underplating and offscraping (Moore et al., 1982). No forearc basin such as those seen on many trench slopes is evident on seismic line MX-16.