When an alarm occurs, it will be displayed on the map with the red radius at the location where the event is reported. By default, the icon color is red, you can change to different color and the icon as well. Read this post.
As shown below is Alarm Clusters which means 17 alarms from that area, please zoom in to see individual alarms.
The clustering can be disabled, go to Workspace –> Workspace Settings –> Marker Clustering set to “No” then click OK.