Benefits from increased development include what?

Lines of longitude are like stripes from the top of the globe down to the bottom virtually slicing the earth like an orange

This is a 2017 topographic map of puerto rico in the united states, and i'm sorry that people there have suffered such a disaster. i want to ask, what do the yellow dots and areas represent on this graph? and the blue area and the little blue circle, and the little blue sign that looks like a signal tower, what do they stand for?

What is the thickest layer of earth called?