While the media tends to cover the well-known San Andreas fault when speaking about the potential danger of a massive earthquake in the Los Angeles basin, the Puente Hills fault system may in fact be equally, if not more, threatening. Discovered four years ago, the extensive fault system is capable of generating earthquakes up to a 7.5 on the Richter scale, and it runs immediately under downtown Los Angeles. The full extent of the fault system was not revealed until 1999, when two geologists were given access to previously secret oil company exploration data that revealed geologic structures beneath the surface. Another disturbing fact was the discovery that the orientation of the Puente Hills fault is directed to focus seismic energy towards downtown L.A., particularly when compared to the Northridge quake of 1994, whose energy was directed away from the downtown area. On a more positive note, James Dolan, a University of Southern California geologist, noted that massive earthquakes do not happen with great frequency and that certain precautions could be taken to stabilize structures in the meantime.

The first link leads to a news article on the Puente Hills fault from today's Los Angeles Times. The second link leads to an article discussing the recent research on the fault system undertaken by James Dolan and his colleagues at the University of Southern California. The third link will take users to the Web site of the Southern California Earthquake Center, which contains up-to-date information on seismic activity in California, along with providing specifics of how earthquakes work and the ability to sign up for email updates from the Center. The fourth link leads to a detailed report and assessment of the 1994 Northridge earthquake in California, which killed 57 people and caused approximately $40 billion dollars in damage. The fifth link leads to the National Earthquake Information Center Web site, which features information about recent seismic activity in the United States and around the world, along with detailed scientific data about the magnitude and scope of recent and historically significant earthquakes. The sixth link takes visitors to a fascinating Web site devoted to telling the story of the New Madrid, Missouri earthquakes of 1811 and 1812, which (it is thought) measured over 8.0 on the Richter scale and temporarily reversed the flow of Mississippi River. Provided by the United States Geological Survey Earthquake Hazards program, the final site lists the largest earthquakes in the United States and provides seismic maps where available.