Events: Events make up the realm of things that might happen to a character such as an earthquake, landslide, or other natural disaster.
Event Encounters: Mortal event encounters are also rated from 1-100 are similar to monster encounters but instead of the strength of an enemy they represent the strength of an enviornmental obsticle. They could represent a wide number of events from a simple trap, to a a complex magical mystery. A level 1 event might represent an obvious track to be followed, or a power level 12 event might be a massive maze to be navigated. They could be a voluntary meaning you have to participate to advance it or they can be unplanned in which case they are sprung on the character without any ability to avoid them. They usually require noncombat skills to overcome can also vary in duration depending on the event. Despite the name they are not just routine events and can be just as deadly and as rewarding as combat. Just see if you can find anyone who has ever climbed a level 100 snow capped mountain searching for treasure and ask them.