The Society for Earthquake and Civil Engineering Dynamics (SECED):
http://www.seced.org.uk/

Institute of Structural Engineers:
http://www.istructe.org/

Earthquake Engineering Research Institute:
http://www.eeri.org/

A central resource which provides links to the sites of other disaster management related organisations:
http://www.disaster-resource.com/content_page/non_profit.shtml

ReliefWeb: a UN coordinated hub for information on Natural Disasters and Complex Emergencies.
http://www.reliefweb.int

BBC natural disasters site: a repository of information that also provides up to the minute reporting.
http://www.bbc.co.uk/science/hottopics/naturaldisasters/

A real-time, world-wide earthquake locator site run by the University of Edinburgh University:
http://tsunami.geo.ed.ac.uk/local-bin/quakes/mapscript/home.pl

The National Earthquake Information Centre:
http://earthquake.usgs.gov/regional/neic/