Data Layer: Earthquakes

This example creates three different presentation styles for a dataset from the USGS recent earthquakes feed.

Check out the reference documentation for the data layer.

Default style

Default style: map

Default style: code example

TypeScript

let map: google.maps.Map;

function initMap(): void {
  map = new google.maps.Map(document.getElementById("map") as HTMLElement, {
    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
  const 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: any) {
  map.data.addGeoJson(data);
}

declare global {
  interface Window {
    initMap: () => void;
    eqfeed_callback: (results: any) => void;
  }
}
window.initMap = initMap;
window.eqfeed_callback = eqfeed_callback;

JavaScript

let 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
  const 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);
}

window.initMap = initMap;
window.eqfeed_callback = eqfeed_callback;

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;
}

HTML

<html>
  <head>
    <title>Default Data Layer: Earthquakes</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>

    <!-- 
     The `defer` attribute causes the callback to execute after the full HTML
     document has been parsed. For non-blocking uses, avoiding race conditions,
     and consistent behavior across browsers, consider loading using Promises
     with https://www.npmjs.com/package/@googlemaps/js-api-loader.
    -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
      defer
    ></script>
  </body>
</html>

Try Sample

Simple style

Simple style: map

Simple style: code example

TypeScript

let map: google.maps.Map;

function initMap(): void {
  map = new google.maps.Map(document.getElementById("map") as HTMLElement, {
    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
  const script = document.createElement("script");

  script.setAttribute(
    "src",
    "https://storage.googleapis.com/mapsdevsite/json/quakes.geo.json"
  );
  document.getElementsByTagName("head")[0].appendChild(script);

  // Add a basic style.
  map.data.setStyle((feature) => {
    const mag = Math.exp(parseFloat(feature.getProperty("mag"))) * 0.1;
    return /** @type {google.maps.Data.StyleOptions} */ {
      icon: {
        path: google.maps.SymbolPath.CIRCLE,
        scale: mag,
        fillColor: "#f00",
        fillOpacity: 0.35,
        strokeWeight: 0,
      },
    };
  });
}

// Defines the callback function referenced in the jsonp file.
function eqfeed_callback(data: any) {
  map.data.addGeoJson(data);
}

declare global {
  interface Window {
    initMap: () => void;
    eqfeed_callback: (results: any) => void;
  }
}
window.initMap = initMap;
window.eqfeed_callback = eqfeed_callback;

JavaScript

let 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
  const script = document.createElement("script");

  script.setAttribute(
    "src",
    "https://storage.googleapis.com/mapsdevsite/json/quakes.geo.json"
  );
  document.getElementsByTagName("head")[0].appendChild(script);
  // Add a basic style.
  map.data.setStyle((feature) => {
    const mag = Math.exp(parseFloat(feature.getProperty("mag"))) * 0.1;
    return /** @type {google.maps.Data.StyleOptions} */ {
      icon: {
        path: google.maps.SymbolPath.CIRCLE,
        scale: mag,
        fillColor: "#f00",
        fillOpacity: 0.35,
        strokeWeight: 0,
      },
    };
  });
}

// Defines the callback function referenced in the jsonp file.
function eqfeed_callback(data) {
  map.data.addGeoJson(data);
}

window.initMap = initMap;
window.eqfeed_callback = eqfeed_callback;

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;
}

HTML

<html>
  <head>
    <title>Simple Data Layer: Earthquakes</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>

    <!-- 
     The `defer` attribute causes the callback to execute after the full HTML
     document has been parsed. For non-blocking uses, avoiding race conditions,
     and consistent behavior across browsers, consider loading using Promises
     with https://www.npmjs.com/package/@googlemaps/js-api-loader.
    -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
      defer
    ></script>
  </body>
</html>

Try Sample

Advanced style

Advanced style: map

Advanced style: code example

TypeScript

let map: google.maps.Map;

function initMap(): void {
  map = new google.maps.Map(document.getElementById("map") as HTMLElement, {
    center: { lat: 20, lng: -160 },
    zoom: 2,
    styles: mapStyle,
  });

  map.data.setStyle(styleFeature);

  // 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
  const 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: any) {
  map.data.addGeoJson(data);
}

function styleFeature(feature: google.maps.Data.Feature) {
  const low = [151, 83, 34]; // color of mag 1.0
  const high = [5, 69, 54]; // color of mag 6.0 and above
  const minMag = 1.0;
  const maxMag = 6.0;

  // fraction represents where the value sits between the min and max
  const fraction =
    (Math.min(feature.getProperty("mag"), maxMag) - minMag) / (maxMag - minMag);

  const color = interpolateHsl(low, high, fraction);

  return {
    icon: {
      path: google.maps.SymbolPath.CIRCLE,
      strokeWeight: 0.5,
      strokeColor: "#fff",
      fillColor: color,
      fillOpacity: 2 / feature.getProperty("mag"),
      // while an exponent would technically be correct, quadratic looks nicer
      scale: Math.pow(feature.getProperty("mag"), 2),
    },
    zIndex: Math.floor(feature.getProperty("mag")),
  };
}

function interpolateHsl(lowHsl: number[], highHsl: number[], fraction: number) {
  const color: number[] = [];

  for (let i = 0; i < 3; i++) {
    // Calculate color based on the fraction.
    color.push((highHsl[i] - lowHsl[i]) * fraction + lowHsl[i]);
  }

  return "hsl(" + color[0] + "," + color[1] + "%," + color[2] + "%)";
}

const mapStyle: google.maps.MapTypeStyle[] = [
  {
    featureType: "all",
    elementType: "all",
    stylers: [{ visibility: "off" }],
  },
  {
    featureType: "landscape",
    elementType: "geometry",
    stylers: [{ visibility: "on" }, { color: "#fcfcfc" }],
  },
  {
    featureType: "water",
    elementType: "labels",
    stylers: [{ visibility: "off" }],
  },
  {
    featureType: "water",
    elementType: "geometry",
    stylers: [{ visibility: "on" }, { hue: "#5f94ff" }, { lightness: 60 }],
  },
];

declare global {
  interface Window {
    initMap: () => void;
    eqfeed_callback: (results: any) => void;
  }
}
window.initMap = initMap;
window.eqfeed_callback = eqfeed_callback;

JavaScript

let map;

function initMap() {
  map = new google.maps.Map(document.getElementById("map"), {
    center: { lat: 20, lng: -160 },
    zoom: 2,
    styles: mapStyle,
  });
  map.data.setStyle(styleFeature);

  // 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
  const 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);
}

function styleFeature(feature) {
  const low = [151, 83, 34]; // color of mag 1.0
  const high = [5, 69, 54]; // color of mag 6.0 and above
  const minMag = 1.0;
  const maxMag = 6.0;
  // fraction represents where the value sits between the min and max
  const fraction =
    (Math.min(feature.getProperty("mag"), maxMag) - minMag) / (maxMag - minMag);
  const color = interpolateHsl(low, high, fraction);
  return {
    icon: {
      path: google.maps.SymbolPath.CIRCLE,
      strokeWeight: 0.5,
      strokeColor: "#fff",
      fillColor: color,
      fillOpacity: 2 / feature.getProperty("mag"),
      // while an exponent would technically be correct, quadratic looks nicer
      scale: Math.pow(feature.getProperty("mag"), 2),
    },
    zIndex: Math.floor(feature.getProperty("mag")),
  };
}

function interpolateHsl(lowHsl, highHsl, fraction) {
  const color = [];

  for (let i = 0; i < 3; i++) {
    // Calculate color based on the fraction.
    color.push((highHsl[i] - lowHsl[i]) * fraction + lowHsl[i]);
  }
  return "hsl(" + color[0] + "," + color[1] + "%," + color[2] + "%)";
}

const mapStyle = [
  {
    featureType: "all",
    elementType: "all",
    stylers: [{ visibility: "off" }],
  },
  {
    featureType: "landscape",
    elementType: "geometry",
    stylers: [{ visibility: "on" }, { color: "#fcfcfc" }],
  },
  {
    featureType: "water",
    elementType: "labels",
    stylers: [{ visibility: "off" }],
  },
  {
    featureType: "water",
    elementType: "geometry",
    stylers: [{ visibility: "on" }, { hue: "#5f94ff" }, { lightness: 60 }],
  },
];

window.initMap = initMap;
window.eqfeed_callback = eqfeed_callback;

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;
}

HTML

<html>
  <head>
    <title>Advanced Data Layer: Earthquakes</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>

    <!-- 
     The `defer` attribute causes the callback to execute after the full HTML
     document has been parsed. For non-blocking uses, avoiding race conditions,
     and consistent behavior across browsers, consider loading using Promises
     with https://www.npmjs.com/package/@googlemaps/js-api-loader.
    -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
      defer
    ></script>
  </body>
</html>

Try Sample