GeoJSON.html

<!DOCTYPE html>
<html>
  <head>
    <title>Default Data Layer: Earthquakes</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="initial-scale=1.0" />
    <style type="text/css">
      /* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
      #map {
        height: 100%;
      }
      /* Optional: Makes the sample page fill the window. */
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
    </style>
  </head>
  <body id="map-container">
    <div id="map"></div>
    <script>

// [START script-body]
      var map;

      function initMap() {
        map = new google.maps.Map(document.getElementById('map'), {
          center: { lat: 20, lng: -160 },
          zoom: 2
        });

        // Get the earthquake data (JSONP format)
        // This feed is a copy from the USGS feed, you can find the originals here:
        //   http://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php
        var script = document.createElement('script');
        script.setAttribute(
            'src',
            'https://storage.googleapis.com/mapsdevsite/json/quakes.geo.json');
        document.getElementsByTagName('head')[0].appendChild(script);
      }

      // Defines the callback function referenced in the jsonp file.
      function eqfeed_callback(data) {
        map.data.addGeoJson(data);
      }
// [END script-body]

    </script>
    <script async defer
        src="https://maps.googleapis.com/maps/api/js?key=AIzaSyDRSwXzXpiCyiILELUd8_FdXBvVewBUIrU&callback=initMap"></script>
  </body>
</html>