MEDLINE's indexing taxonomy, MeSH, has a head term disasters with several levels and multiple terms below it
Depending on the specificity of what you need, this might be a useful place to start.
In case you don't know how to get there:
Go to PubMed.gov
In the search box, type. disasters
But before pressing the SEARCH button, use the pull down menu to the left of the search box to choose MeSH
Clicking on the terms will bring up definitions, year the terms was added, previous terms if they exist, etc.
It's not perfect. '˜Tidal waves' is under Disasters. '˜Tsunamis' is in a different part of the taxonomy entirely, so do use creativity in looking for related terms and how the taxonomy is constructed. I'm glad to explain more if I can be of help.
Pamela C. Sieving
Sieving Information Solutions
HIFA profile: Pamela Sieving is a special volunteer at the National Eye Institute/National Institutes of Health, and an independent consultant in biomedical information access; she works primarily in the vision community to increase access to information needed to preserve and restore vision. pamsieving AT gmail.com