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

gre

Default style: code example

TypeScript

let innerMap;
let earthquakeData;

async function initMap() {
  (await google.maps.importLibrary("maps")) as google.maps.MapsLibrary;

  const mapElement = document.querySelector(
    "gmp-map"
  ) as google.maps.MapElement;

  innerMap = mapElement.innerMap;

    // 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",
    "quakes.geo.json"
  );

  document.getElementsByTagName("head")[0].appendChild(script);
}

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

window.eqfeed_callback = eqfeed_callback;
initMap();
index.ts

JavaScript

let innerMap;
let earthquakeData;
async function initMap() {
    (await google.maps.importLibrary("maps"));
    const mapElement = document.querySelector("gmp-map");
    innerMap = mapElement.innerMap;
    // 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", "quakes.geo.json");
    document.getElementsByTagName("head")[0].appendChild(script);
}
// Defines the callback function referenced in the jsonp file.
function eqfeed_callback(data) {
    innerMap.data.addGeoJson(data);
}
window.eqfeed_callback = eqfeed_callback;
initMap();
index.js

CSS

/* 
 * Always set the map height explicitly to define the size of the div element
 * that contains the map. 
 */
gmp-map {
  height: 100%;
}

/* 
 * Optional: Makes the sample page fill the window. 
 */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

style.css

HTML

<html>
  <head>
    <title>Default Data Layer: Earthquakes</title>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>

    <!-- prettier-ignore -->
    <script>(g=>{var h,a,k,p="The Google Maps JavaScript API",c="google",l="importLibrary",q="__ib__",m=document,b=window;b=b[c]||(b[c]={});var d=b.maps||(b.maps={}),r=new Set,e=new URLSearchParams,u=()=>h||(h=new Promise(async(f,n)=>{await (a=m.createElement("script"));e.set("libraries",[...r]+"");for(k in g)e.set(k.replace(/[A-Z]/g,t=>"_"+t[0].toLowerCase()),g[k]);e.set("callback",c+".maps."+q);a.src=`https://maps.${c}apis.com/maps/api/js?`+e;d[q]=f;a.onerror=()=>h=n(Error(p+" could not load."));a.nonce=m.querySelector("script[nonce]")?.nonce||"";m.head.append(a)}));d[l]?console.warn(p+" only loads once. Ignoring:",g):d[l]=(f,...n)=>r.add(f)&&u().then(()=>d[l](f,...n))})
        ({key: "AIzaSyA6myHzS10YXdcazAFalmXvDkrYCp5cLc8", v: "weekly"});</script>
  </head>
  <body>
    <gmp-map center="20,-160" zoom="3"></gmp-map>
  </body>
</html>
index.html

Try Sample

Simple style

Simple style: map

Simple style: code example

TypeScript

let innerMap;

async function initMap() {
  (await google.maps.importLibrary("maps")) as google.maps.MapsLibrary;

  const mapElement = document.querySelector(
    "gmp-map"
  ) as google.maps.MapElement;

  innerMap = mapElement.innerMap;

  // 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",
    "quakes.geo.json"
  );

  document.getElementsByTagName("head")[0].appendChild(script);

  // Add a basic style.
  innerMap.data.setStyle((feature) => {
    const mag = Math.exp(parseFloat(feature.getProperty("mag") as string)) * 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) {
  innerMap.data.addGeoJson(data);
}

window.eqfeed_callback = eqfeed_callback;
initMap();
index.ts

JavaScript

let innerMap;
async function initMap() {
    (await google.maps.importLibrary("maps"));
    const mapElement = document.querySelector("gmp-map");
    innerMap = mapElement.innerMap;
    // 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", "quakes.geo.json");
    document.getElementsByTagName("head")[0].appendChild(script);
    // Add a basic style.
    innerMap.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) {
    innerMap.data.addGeoJson(data);
}
window.eqfeed_callback = eqfeed_callback;
initMap();
index.js

CSS

/* 
 * Always set the map height explicitly to define the size of the div element
 * that contains the map. 
 */
gmp-map {
  height: 100%;
}

/* 
 * Optional: Makes the sample page fill the window. 
 */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

style.css

HTML

<html>
  <head>
    <title>Simple Data Layer: Earthquakes</title>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>

    <!-- prettier-ignore -->
    <script>(g=>{var h,a,k,p="The Google Maps JavaScript API",c="google",l="importLibrary",q="__ib__",m=document,b=window;b=b[c]||(b[c]={});var d=b.maps||(b.maps={}),r=new Set,e=new URLSearchParams,u=()=>h||(h=new Promise(async(f,n)=>{await (a=m.createElement("script"));e.set("libraries",[...r]+"");for(k in g)e.set(k.replace(/[A-Z]/g,t=>"_"+t[0].toLowerCase()),g[k]);e.set("callback",c+".maps."+q);a.src=`https://maps.${c}apis.com/maps/api/js?`+e;d[q]=f;a.onerror=()=>h=n(Error(p+" could not load."));a.nonce=m.querySelector("script[nonce]")?.nonce||"";m.head.append(a)}));d[l]?console.warn(p+" only loads once. Ignoring:",g):d[l]=(f,...n)=>r.add(f)&&u().then(()=>d[l](f,...n))})
        ({key: "AIzaSyA6myHzS10YXdcazAFalmXvDkrYCp5cLc8", v: "weekly"});</script>
  </head>
  <body>
    <gmp-map center="20,-160" zoom="2"></gmp-map>
  </body>
</html>
index.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
  let mag = feature.getProperty("mag") as number;
  const fraction =
    (Math.min(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 / mag,
      // while an exponent would technically be correct, quadratic looks nicer
      scale: Math.pow(mag, 2),
    },
    zIndex: Math.floor(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;
index.ts

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
  let mag = feature.getProperty("mag");
  const fraction = (Math.min(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 / mag,
      // while an exponent would technically be correct, quadratic looks nicer
      scale: Math.pow(mag, 2),
    },
    zIndex: Math.floor(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;
index.js

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.css

HTML

<html>
  <head>
    <title>Advanced Data Layer: Earthquakes</title>

    <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 script 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. See
      https://developers.google.com/maps/documentation/javascript/load-maps-js-api
      for more information.
      -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
      defer
    ></script>
  </body>
</html>
index.html

Try Sample