How can an earthquake with a moderate magnitude have a high intensity?

The intensity of earthquake or the amount of damage an earthquake causes depends on multiple factors, not just its magnitude. These factors include focal depth, distance from epicenter, design of buildings, population of area, etc. If an earthquake of 4.7 magnitude occurs underneath a well-populated area and the epicenter was closer to the surface, then it will cause more damage compared to an earthquake of magnitude 6 or 7 which is 20 miles or so away.