The Richter scale doesn't measure quake damage (see: Mercalli Scale) which is dependent on a variety of factors including population at the epicentre, terrain, depth, etc.
The circulatory system works with the muscular system, the nervous system, and the digestive system. The heart is a muscle so it is part of the muscular system. Also the heart and lungs have nerves so it is also part of the nervous system.
The heart, the lungs, and the veins and arteries (blood vessels) make up the circulatory system. Working together, they ensure that blood flows through the whole network that makes up the human body (systemic circulation), as well as within the lungs (pulmonary circulation) and the heart (coronary circulation).