Earthquakes on the Map

Field notes

The visualization represents earthquake epicenters as circles whose size corresponds approximately to magnitude and whose colour corresponds to focal depth. Its controls support individual years, five-year windows, decades, cumulative history, and minimum-magnitude thresholds from 4.5 through 7.0. The accompanying text uses the plotted record to explain the Ring of Fire, the Alpide belt, mid-ocean ridges, subduction zones, and the distinction between epicenters and underground hypocenters.