This heatmap displays earthquake counts across U.S. states for each year from 2010 to 2015, filtered by magnitude category via a dropdown selector. The visualization uses a quantized color scale to encode count values, with tooltips revealing exact numbers on hover. Built with D3 v5, it renders SVG rectangles positioned by band scales for states and years, and updates dynamically through a change event listener. The data is loaded from an external CSV file and grouped using d3.nest.