Virtual Mailing List Managers?
stan7826 asks: "I'm the sysadmin for the USGS Earthquake Hazards Program here in Southern California, and we currently run a small set of public mailing lists for earthquake information. We currently have a set of five lists. Two for long messages, two for short pager-style messages, and one for an ASCII-art map of earthquake shaking. People can subscribe to the list they want from our web page. But we are now looking at making this a statewide service, with a sort of cafeteria-style interface. We want for people to be able to select what events they get notified for by region, magnitude and message type. If I just create a mailing list for each combination, I get 24 different lists for California. This is just begging for some sort of database-driven virtual mailing list manager. Does anyone know of such a beast? (Preferably open-source, of course!)"
If you can't find something suittable, and you have the time, writing one yourself might be a good investment.
/trying to stay away from mentioning any specific language or db.
Use your choice of web language to add email addresses to the database.
Then use something like perl to fire off the emails, depending on what the subscriber wants.
As the other poster said, you'll probably have to write this yourself. I recommend looking at TIGER and FIPS, which may allow you to have your program be completely dynamic--people could choose to be alerted of seismic events within 100, 500, 1000 miles of their home relatively easily. (I'm not familiar with either of these services, but I remembered their use by the winner of the Google Programming Contest.)
Now for magnitude, you can just flag each seismic event with an appropriate value and see if it meets the threshold the citizens want. And since you have the distance from the epicenter to the citizen's home, you can calculate the effective magnitude that the citizen feels, or you can just leave it as the magnitude found at the epicenter.
sympa http://www.sympa.org might do what you want, through its cross-db and ldap capabilities, you might want to take a look.