Seismic shutoff valve
An automatic valve that cuts gas to the house when it senses earthquake shaking.
A seismic (or earthquake) gas shutoff valve is an automatic device installed on the gas line that closes by itself when it detects strong shaking, cutting fuel before a ruptured line can feed a fire. Some jurisdictions in high-risk seismic areas require one on new or sold homes. It only stops the gas — like any gas shutoff, it must be reset and the system checked by your gas utility or a qualified professional before service is restored; never reopen gas yourself. A seismic valve is a complement to, not a replacement for, knowing how to operate your manual [gas shutoff valve](/glossary/gas-shutoff-valve) — learn both in [how to shut off your utilities in an emergency](/guides/how-to-shut-off-utilities-in-an-emergency).