Final answer:
The manager of a food establishment should first ensure the safety of the staff and customers in the event of an earthquake disrupting the power and water supply. Then, the manager should assess the damage and contact relevant authorities or utility companies to restore the supplies.
Step-by-step explanation:
In the event of an earthquake disrupting a food establishment's power and water supply, the manager must first ensure the safety of the staff and customers present at the time. This may involve evacuating the building if necessary. Once everyone is safely out of harm's way, the manager should then assess the damage and contact relevant authorities or utility companies to restore the power and water supply.