Resetting a seismic gas shut-off valve involves a careful process to ensure safety. First, assess the area for gas leaks or odors, evacuating if necessary. Inspect the valve to verify it's in the closed position due to seismic activity. Some valves have reset buttons; if present, press them according to the manufacturer's instructions. Then, cautiously turn on a gas appliance to test gas flow restoration. If uncertain or encountering issues, consult a licensed professional. Safety is paramount, so always prioritize caution and expert assistance for the proper operation of gas-related equipment.