Earthquake gas shutoff valves only trigger at magnitude 5.4+, missing smaller fires

Seismic gas shutoff valves, which cost $250-$750 installed, automatically close a building's gas supply when they detect earthquake shaking. However, they are calibrated to activate only at shaking equivalent to approximately magnitude 5.4 or greater on the Richter scale. This means that a magnitude 4.5-5.3 earthquake, which can still rupture aging gas lines, shift foundations, and crack pipe joints, will not trigger the valve. One in four post-earthquake fires is linked to natural gas leaks, and many of these fires start from moderate earthquakes or aftershocks that fall below the valve's activation threshold. Homeowners and renters who installed these valves believe they are protected, but they have a false sense of security for the most common damaging earthquake scenarios. Meanwhile, excess flow valves (EFVs) that detect abnormal gas flow regardless of shaking magnitude cost $2,500-$5,000 to install, pricing them out of reach for most homeowners. The problem persists because the seismic valve industry standardized on the 5.4 threshold decades ago, there is no regulatory requirement to install flow-based detection instead, and most homeowners do not understand the technical limitations of their installed valve.