There are a variety of special maps listed on each page. These special maps cover selected areas in greater detail. We can't allow arbitrary zooming in because this would mean creating maps for each individual user and our servers could not handle that load. You may want to bookmark the index page on the various mirror sites as well as the more detailed maps for the area where you live and work and others that you find interesting. This may help you get fast access after significant earthquakes when many people are trying to use the Recent Earthquakes system.
Some users prefer to see earthquakes drawn as circles.
We have chosen to use squares because computer screens are based on a square grid of dots or rasters. This makes it easier to draw a clear square than a circle. To draw a good looking circle requires a technique called anti-aliasing, however this introduces shades of grey into the image which makes the map files larger and that makes them transfer more slowly. We agree that circles are prettier than squares, and we anticipate that as software and hardware get better and faster, it will be more feasible to use circles. Right now we have opted for the simplicity and visual clarity of squares.