If a substantial amount of calcium is discovered, coronary artery disease may be likely. A CT coronary angiogram, in which you receive a contrast dye injected intravenously during a CT scan, also can generate images of your heart arteries.
At converging plate boundaries, two situations are possible. First, both volcanoes and earthquakes form where one plate sinks under the other. This process, called subduction, takes place because one plate is denser than the other. The denser plate, which invariably has oceanic crust on its top, does the sinking. Second, only earthquakes occur when two plates collide (obduct), building a mountain range.
What Causes Earthquakes. Earthquakes occur when the rocks (or plates) lying under earth's surface push against each other and break. This can happen with the rocks lying under the landmass, or those under the seawater. This causes earthquakes, during which the rocks move against each other until they settle again.