There are three levels of activation for the Emergency Operations Center (EOC) - none, limited, and full.
There is no need for the EOC to be activated, because all aspects of the incident can be handled by the on-scene incident command post and/or a department operations center (DOC).
For small incidents that impact large areas or complex incidents within a small area that impact a large number of agencies and the public (e.g., hazardous materials incident, terrorist attack, etc.), the incident commander may elect to call in a limited number of EOC staff. The specific functions / positions activated are based on incident demands, with primary consideration being given to:
Message Center Manager
Public Information Officer (PIO)
For larger incidents, the entire EOC team is called in for a full activation of the EOC. After activation of the EOC and initial briefing of the staff, the incident commander may reduce the level of staffing needed to support response activities.