Answer:
They help to show the driving force of the explosive eruptions and the viscosity shows whether the eruption would be explosive or not
Sea floor spreading adds more crust to the ocean floor and at the same time older strips of rock move outward from either side of the ridge.
Answer:
This is a Topographic map.
Explanation:
Topographic maps are a detailed record of a land area, giving geographic positions and elevations for both natural and man-made features. They show the shape of the land the mountains, valleys, and plains by means of brown contour lines (lines of equal elevation above sea level).
Hoped this helped.