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.
Why volcanoes occur near subduction zones: compression heats the rocks; the descending slab begins to melt; hot rocks is uplifted by mountain-building events; tension opens cracks so material from the core can rise. The San Andreas Fault is: a transform fault; a subduction zone; a rift valley; a zone of collision between two continents