It's a hypothetical scenario, but members of the Yass Valley Local Emergency Management Committee including NSW Police Force, Fire and Rescue, State Emergency Service, Health, Disaster Welfare, Binalong Rescue Squad, Rural Fire Service, Ambulance, Local Land Services and Yass Valley Council took those questions seriously in an emergency operations centre (EOC) exercise on Tuesday.

Regional emergency management officer Paul Lloyd said the annual exercise gives emergency services a chance to prepare for a realistic, local hazard.

"We have a lot of earthquakes in this area which do not impact on community but we must still be prepared," he said.

"Each person has a role and responsibility in the EOC so the local emergency operations controller (LEOCON) can ensure timely provision of support to affected communities," said acting Inspector David Cowell of Yass Police Station, who was LEOCON on Tuesday.

To make the situation as realistic as possible, the LEOCON activated an EOC in Yass and notified the council local emergency management officer.

Agencies were then called to the EOC and their response time was recorded.

In their positions, tabards, phones, white boards, forms and laptops came out and everyone began working on how best to assist the community.

Acting health services manager at Yass Hospital, Nikki Barnes, was responsible for organising the triage of patients and which patients needed to be transferred to other hospitals, while working with other agencies.

District WelFAC (functional area coordinator) for Illawarra Shoalhaven and Southern NSW with Disaster Welfare, Richard Linfoot, was training other staff from his department to act as a liaison officer in an EOC during an emergency.

"The main thing we do is set up evacuation centres," he said.

"Today's scenario was not too dissimilar to what it's actually like. It was quite realistic.

"These are excellent opportunities for us to practice an emergency in a safe environment and it helps to build confidence."

This year's exercise "went well", regional emergency management officer Mr Lloyd said.

"We want to praise the team. It really is a dedicated group of people who come together in an emergency."

Acting Inspector Cowell said everyone had taken time out of their day to take part in the exercise.

"You've got paid agency members and volunteers working side-by-side," Mr Lloyd said.

Another and more likely hazard emergency services are preparing for is, of course, bush fires this summer.

"We only have to look up north to know this isn't pie in the sky thinking and we need to be at our best. We consistently ask the community to plan and be prepared and we are not different. We need to prepared across the region to respond," Mr Lloyd said.