Seismic Alert System (SAS)

The Seismic Alert System (SAS) is a technology that detects early signs of an earthquake by monitoring seismic waves. When minor preliminary waves (called P-waves) are detected, the system quickly analyzes their strength and origin. If an earthquake is imminent, it sends alerts seconds to minutes before the more destructive secondary waves (S-waves) arrive. This advance warning gives people and systems time to take protective actions, such as “drop, cover, and hold,” or automatically stopping trains and shutting down infrastructure, helping to reduce injuries and damages.