The Stephens Library has a large number of books on natural disasters. Some of these are shown on the left hand side of the page. Use the catalogue to search for other books. Try narrowing your results by searching for a specific type of disasters such as volcanoes or earthquakes.
Britannica online provides great information, images and videos on natural disasters. You are free to use the images in your assignment, providing you reference them. Go back to the main Library page to search Britannica. Check out the link on the left hand side that provides a link to the 'web's best', which links to relevant web resources.
This site provides information on all types of natural disasters and why they occur.
Geoscience Australia provides information on bushfires, cyclones, earthquakes, floods, tsunamis, volcanoes and landslides. The most relevant information can be found by selecting the section that provides basic information for these disasters. For example, 'Earthquake Basics' or 'Bushfire Basics'.
ABC Splash provides some great videos on a range of natural disasters. Search for 'natural disasters' or a specific disaster such as 'volcaones'.