The US Geological Survey makes available a small dataset containing the M1+ earthquakes from around the world in the past 7 days . I used this data along with the heatmap visualization layer offered by the Google Maps API to present the earthquake data as a heatmap. Check out Worldwide M1+ Earthquakes, Past 7 Days . One caveat: due to cross origin issues, I am hosting a local copy of the data rather than getting it live from the USGS.
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