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Create a heatmap layer

Visualize earthquake frequency by location using a heatmap layer.

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Create a heatmap layer</title>
    <meta property="og:description" content="Visualize earthquake frequency by location using a heatmap layer." />
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel='stylesheet' href='https://unpkg.com/maplibre-gl@4.4.0/dist/maplibre-gl.css' />
    <script src='https://unpkg.com/maplibre-gl@4.4.0/dist/maplibre-gl.js'></script>
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 100%; }
    </style>
</head>
<body>
<div id="map"></div>

<script>
    const map = new maplibregl.Map({
        container: 'map',
        style:
            'https://api.maptiler.com/maps/basic/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
        center: [-120, 50],
        zoom: 2
    });

    map.on('load', () => {
        // Add a geojson point source.
        // Heatmap layers also work with a vector tile source.
        map.addSource('earthquakes', {
            'type': 'geojson',
            'data':
                'https://maplibre.org/maplibre-gl-js/docs/assets/earthquakes.geojson'
        });

        map.addLayer(
            {
                'id': 'earthquakes-heat',
                'type': 'heatmap',
                'source': 'earthquakes',
                'maxzoom': 9,
                'paint': {
                    // Increase the heatmap weight based on frequency and property magnitude
                    'heatmap-weight': [
                        'interpolate',
                        ['linear'],
                        ['get', 'mag'],
                        0,
                        0,
                        6,
                        1
                    ],
                    // Increase the heatmap color weight weight by zoom level
                    // heatmap-intensity is a multiplier on top of heatmap-weight
                    'heatmap-intensity': [
                        'interpolate',
                        ['linear'],
                        ['zoom'],
                        0,
                        1,
                        9,
                        3
                    ],
                    // Color ramp for heatmap.  Domain is 0 (low) to 1 (high).
                    // Begin color ramp at 0-stop with a 0-transparency color
                    // to create a blur-like effect.
                    'heatmap-color': [
                        'interpolate',
                        ['linear'],
                        ['heatmap-density'],
                        0,
                        'rgba(33,102,172,0)',
                        0.2,
                        'rgb(103,169,207)',
                        0.4,
                        'rgb(209,229,240)',
                        0.6,
                        'rgb(253,219,199)',
                        0.8,
                        'rgb(239,138,98)',
                        1,
                        'rgb(178,24,43)'
                    ],
                    // Adjust the heatmap radius by zoom level
                    'heatmap-radius': [
                        'interpolate',
                        ['linear'],
                        ['zoom'],
                        0,
                        2,
                        9,
                        20
                    ],
                    // Transition from heatmap to circle layer by zoom level
                    'heatmap-opacity': [
                        'interpolate',
                        ['linear'],
                        ['zoom'],
                        7,
                        1,
                        9,
                        0
                    ]
                }
            },
            'waterway'
        );

        map.addLayer(
            {
                'id': 'earthquakes-point',
                'type': 'circle',
                'source': 'earthquakes',
                'minzoom': 7,
                'paint': {
                    // Size circle radius by earthquake magnitude and zoom level
                    'circle-radius': [
                        'interpolate',
                        ['linear'],
                        ['zoom'],
                        7,
                        ['interpolate', ['linear'], ['get', 'mag'], 1, 1, 6, 4],
                        16,
                        ['interpolate', ['linear'], ['get', 'mag'], 1, 5, 6, 50]
                    ],
                    // Color circle by earthquake magnitude
                    'circle-color': [
                        'interpolate',
                        ['linear'],
                        ['get', 'mag'],
                        1,
                        'rgba(33,102,172,0)',
                        2,
                        'rgb(103,169,207)',
                        3,
                        'rgb(209,229,240)',
                        4,
                        'rgb(253,219,199)',
                        5,
                        'rgb(239,138,98)',
                        6,
                        'rgb(178,24,43)'
                    ],
                    'circle-stroke-color': 'white',
                    'circle-stroke-width': 1,
                    // Transition from heatmap to circle layer by zoom level
                    'circle-opacity': [
                        'interpolate',
                        ['linear'],
                        ['zoom'],
                        7,
                        0,
                        8,
                        1
                    ]
                }
            },
            'waterway'
        );
    });
</script>
</body>
</html>