Yes, earthquake valves, also known as seismic gas shut-off valves, are required in many parts of California. In areas prone to seismic activity, like California, local building codes often mandate the installation of these valves to enhance safety by automatically shutting off the gas supply during earthquakes. These valves help prevent gas leaks and potential fires, safeguarding both property and lives. Compliance with local building codes and regulations is essential, and it's advisable to consult local authorities or HVAC professionals to ensure proper installation and adherence to requirements.