For my homework I was given a velocity diagram of the Juan de Fuca plate similar to this: The first question is as follows: Measurements indicate that the Juan de Fuca plate is moving at a speed of ~40 mm/year. Calculate, and draw diagrams that show, the horizontal and vertical components of this motion at two locations in Figure 2: at x=40 km (ie, well before the Juan de Fuca plate encounters the North American plate), and at x=340 km (ie, after the Juan de Fuca plate has subducted below the North American plate). I'm just super confused on what exactly this question is looking for and where I should even start? I know from the next question that I'm supposed to be finding velocity, but I don't know how to use this diagram to do that. I don't understand how the speed is relevant in comparison to the velocity on the graph and how the velocity would be used if it depends on depth etc. etc. Can someone decipher this question for me and gives me hints on where to go?