Data is being requested in real-time from the USGS GeoJSON Feed.
The size of the circle marker indicate the magnitude of the earthquake, and the color indicates the depth of the earthquake. Each circle marker can be clicked on to prompt a popup box which contains information on the earthquate, ie. location, magnitude, depth and date & time.
A legend is provided to indicate the depth of the earthquake.
A layer control is provided to toggle between different map layers as well as the overlay for earthquake and the tectonic plates visualization.
The project code can be found here.