Up-to-date earthquake data is available from the USGS Earthquake Hazards Program
on the following page:
http://earthquake.usgs.gov/eqcenter/catalogs/
At that site, some of the data is available in kmz format for use in Google
Earth.
You can instead get the same data from the direct links below. Right-click
to download today's data from the links that are in boldface.
A similar file (colored by depth), obtained from the above site on September 13, 2007, is available at:
A Natural Hazards KML file is available from the National
Geophysical Data Center.
The following is a direct link to that data:
Alternatively, you can find the link on the page at: http://www.ngdc.noaa.gov/seg/hazard/