The Emergency Events Database (EM-DAT) is available free online, and is a useful resource for many involved in humanitarian work. As outlined on their website:
"The main objective of the database is to serve the purposes of humanitarian action at national and international levels. It is an initiative aimed to rationalize decision making for disaster preparedness, as well as providing an objective base for vulnerability assessment and priority setting.
EM-DAT contains core data on the occurrence and effects of over 18,000 mass disasters in the world from 1900 to present. The database is compiled from various sources, including UN agencies, non-governmental organisations, insurance companies, research institutes and press agencies."
The database contains records of many geological and atmospherical hazards, as well as other hazards (disease, technological etc). It has data for all continents, and spans over 110 years. Analysis of data for specific regions and areas may produce interesting trends useful for disaster preparedness.