Earthquakes Heatmap

Demonstrates the use of a heatmap layer.

This example parses a KML file and renders the features as a ol/layer/Heatmap layer.

<!DOCTYPE html>
    <title>Earthquakes Heatmap</title>
    <link rel="stylesheet" href="" type="text/css">
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src=",Element.prototype.classList,URL"></script>

    <div id="map" class="map"></div>
      <label>radius size</label>
      <input id="radius" type="range" min="1" max="50" step="1" value="5"/>
      <label>blur size</label>
      <input id="blur" type="range" min="1" max="50" step="1" value="15"/>
      import Map from 'ol/Map.js';
      import View from 'ol/View.js';
      import KML from 'ol/format/KML.js';
      import {Heatmap as HeatmapLayer, Tile as TileLayer} from 'ol/layer.js';
      import Stamen from 'ol/source/Stamen.js';
      import VectorSource from 'ol/source/Vector.js';

      var blur = document.getElementById('blur');
      var radius = document.getElementById('radius');

      var vector = new HeatmapLayer({
        source: new VectorSource({
          url: 'data/kml/2012_Earthquakes_Mag5.kml',
          format: new KML({
            extractStyles: false
        blur: parseInt(blur.value, 10),
        radius: parseInt(radius.value, 10)

      vector.getSource().on('addfeature', function(event) {
        // 2012_Earthquakes_Mag5.kml stores the magnitude of each earthquake in a
        // standards-violating <magnitude> tag in each Placemark.  We extract it from
        // the Placemark's name instead.
        var name = event.feature.get('name');
        var magnitude = parseFloat(name.substr(2));
        event.feature.set('weight', magnitude - 5);

      var raster = new TileLayer({
        source: new Stamen({
          layer: 'toner'

      var map = new Map({
        layers: [raster, vector],
        target: 'map',
        view: new View({
          center: [0, 0],
          zoom: 2

      blur.addEventListener('input', function() {
        vector.setBlur(parseInt(blur.value, 10));

      radius.addEventListener('input', function() {
        vector.setRadius(parseInt(radius.value, 10));