Textbook definitions — you might be able to use.
Many experienced emergency managers get into a job and — stop learning. There are lots of reasons for that to happen. A short list:
Let me touch on this last one with this resource shared by the Recovery Diva, What is a Disaster? $71 for a new text, but they have used ones for $28. The book is a series of essays by different college professors and researchers. I expect this is a textbook for emergency management degree-types of courses.
My suggestion is that you can find time to read. Ideally for me, it is on one of my electronic devices. My "major reading time" is when I grab 5-10 minutes on my M-F commute to work. Currently I'm "still" reading American Dunkirk about the evacuation of Manhattan on 9/11. I'm also reading three other books concurrently — and slowly!
My experience — even recently, is how the book is making me think about disaster response and the need to leverage our nontraditional first responding citizens to be part of our larger disaster response and recovery efforts.
Take time to grab your own few minutes to keep your creative and insightful juices flowing. Don't grow old and stale, limiting your advances in thinking to only experiential events in your professional life. We can learn from others, and reading is a great way to start.