Class 4-Earthquakes in US

<!DOCTYPE html>
<meta charset="utf-8">
<title>Class 4</title>
<style>
body {
  position: absolute;
  margin: 0px;
}
svg {
  background-color: #4682b4;
}
.info {
  font-family: sans-serif;
  color: #000;
  position: absolute;
  top: 450px;
  left: 800px;
}
path {
  fill: #555555;
  stroke: #aaaaaa;
}
/* NEW: style the earthquakes */
path.quake {
  fill: crimson;
}
</style>

<body>
<script>
var width = 960, height = 500;
var data;  // declare a global variable
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
    .on("mousemove", mousemoved);
// NEW: Add one layer (i.e., <g> element) each for states & earthquakes
var layer1 = svg.append("g");
var layer2 = svg.append("g");
// Add a <div> element to label the mouse position
var info = d3.select("body").append("div")
    .attr("class", "info");
var projection = d3.geoAlbersUsa();
var path = d3.geoPath()
    .projection(projection);
// NEW: Read the earthquake data and send it to function "plotQuakes"
var usgs = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson";
// Topojson for US states
var url = "https://umbcvis.github.io/classes/class-03/us.json"
d3.json(url, plotStates);
d3.json(usgs, plotQuakes);
function plotStates(error, json) {
  // Convert topojson to an Array of GeoJSON features
  // This defines "data", a global variable that can be manipulated in the developer console
  data = json.objects.us.geometries.map(function(d) { return topojson.feature(json, d); })
  // Plot the features (states) -- one <path> element for each state
  // NEW: Plot the states in a <g> element
  layer1.selectAll("path")
      .data(data)
    .enter()
      .append("path")
      .attr("d", path);
}
// NEW: Function that plots the earthquake data
function plotQuakes(error, json) {
  if (error) return console.log(error);
  // Global variable, data, will be visible in the console
  data = json;
  // Extract an array of feature objects, one for each earthquake
  var features = json.features;
  // Plot the earthquakes
  layer2.selectAll("path.quake")
      .data(features)
    .enter().append("path")
      .attr("class", "quake")
      .attr("d", path)
}
// Label the geographic coordinates of the mouse position on the map
function mousemoved() {
  info.text(formatLocation(projection.invert(d3.mouse(this)), projection.scale()));
}
// Format the text that will be displayed in the the <div> element on the map
function formatLocation(p, k) {
  var format = d3.format("." + Math.floor(Math.log(k) / 2 - 2) + "f");
  return (p[1] < 0 ? format(-p[1]) + "°S" : format(p[1]) + "°N") + " "
       + (p[0] < 0 ? format(-p[0]) + "°W" : format(p[0]) + "°E");
}
</script>

https://d3js.org/d3.v4.min.js

https://d3js.org/topojson.v2.min.js