Name: date: trench back arc swe weda figure 7: north pacific bathymetry 16. draw the appropriate symbols for a subduction zone and indicate the relative plate motions with arrows for the aleutian are. label the outer swell, trench, accretionary wedge, island arc, and back-are basin. 17. which plate is being subducted (pacific or north american)? how can you tell? octic ol you fnd tu vaicanoes on u wes+ 18. what has been the rate and direction of plate movement during the last 40 million years? (show your work and answer in cm/yr. also indicate compass direction) is this answer reasonable? 19. what has been the rate and direction of plate motion during the period from 40-60 million years ago? (show your work and answer in cm/yr. also indicate compass direction of plate movement) 20. what happened to the rate and direction of the pacifie plate motion 40ma?