A lot of geologic information is shared online, it's up to you to determine whether that information is credible. A few things to think about include:
A few good places to start are federal and state government sites, professional geological societies, and university geology labs.
Geology and Earth Science departments at universities often have great information on their websites. You will sometimes come across student papers, so remember to pay attention to who is responsible for the content you are reading.
It would be too much to link to every geology department and lab. For some countries, you can search for geology information only at universities by doing a google search and adding site: and then the top-level domain for universities to the end of your search. Not all countries have a specific domain for colleges and universities.
Example Google search:
will find websites at New Zealand universities about earthquakes