The earthquake probability maps produced by the US Geological Survey are available to the public and updated hourly.
"These maps graphically illustrate the change in earthquake probability during aftershock and possible foreshock sequences.
...the new maps and the way they were developed are discussed in an article in the current issue of the journal Nature. The methodology was developed by a team from the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, and the U. S. Geological Survey in California, with funding from the Southern California Earthquake Center, ETH and the USGS."
Thanks to Chris Steins