A friend  just showed me QWiki. What a useful tool for students and teachers!  QWiki pulls content for your request from Wikipedia, Google, Photopedia and YouTube. Content is presented as a multi-image montage, with audio narration. Here's the result if you search for "Volcano":

By clicking on the "Content" tab of the results page, you can see all the images used, and have a text transcript of the narration. Related search terms are suggested at the bottom of the page. Direct links for sharing on Facebook, Twitter, email and embedding are available.

As with all search results, some topics will be more reliable than others! The usual caution should be applied when viewing, as the material is only as reliable as what can be found at those 4 sites. But they are presented in a fine package for introductory understanding.

Screen Shot of QWiki on "Earthquake"