Geography (easy access to free global satellite
imagery): http://earth.google.com/
http://vulcan.wr.usgs.gov/home.html
http://volcanoes.usgs.gov/yvo/
http://eos.higp.hawaii.edu/index.html
Earthquakes (national and global)
http://www.consrv.ca.gov/cgs/geologic_hazards/earthquakes/index.htm
http://www.consrv.ca.gov/cgs/smip/index.htm
http://www.consrv.ca.gov/CGS/rghm/ap/index.htm
http://walrus.wr.usgs.gov/elnino/#Landslides
http://walrus.wr.usgs.gov/elnino/landslides-sfbay/
www.usgs.gov/themes/flood.html
http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.024-00.html
http://water.usgs.gov/pubs/circ/2003/circ1245/
Tsunami
http://walrus.wr.usgs.gov/tsunami/
http://walrus.wr.usgs.gov/tsunami/PNGhome.html
http://walrus.wr.usgs.gov/tsunami/cascadia.html
http://walrus.wr.usgs.gov/cascadia/
http://www.consrv.ca.gov/cgs/geologic_hazards/Tsunami/About_Tsunamis.htm
General
Hazards
http://walrus.wr.usgs.gov/hazards/