Earthquake Early Warning

The Earthquake Early Warning System (EEWS) detects the P seismic waves of an earthquake and sends alerts via audio/visual alarms, SMS and/or email. The system can be designed to stop and open the elevator carriage to the nearest floor, shut off gas valves, safely turn off equipment and machines seconds before the S seismic waves (actual shaking) arrive. This system allows the business to execute safety controls, people to perform the duck, cover and hold, stop hazardous works and move to safe locations. How does the Earthquake Early Warning System Works: All earthquakes produce primary or pressure waves (P Waves) and secondary or shear waves (S Waves). Most of the time, P waves are not felt. On the hand, S waves produces the shaking we feel during an earthquake. Considering that the speed of the S wave is just 60% of the speed of the P wave, detection of the P wave will give us ample time to execute safety controls before the destructive shaking starts. Real Life Example: 2025 Cebu Earthquake Magnitude 6.9 Epicenter: Offshore 17.5 kms off Bogo City If there is an EEWS installation at Bogo City, the city will have an advance warning of 1.31 seconds only considering the proximity of the epicenter. However, locations farther from the epicenter where very strong shaking occurred like Cebu City and Negros Occidental have 6.75 and 9.83 seconds warning respectively.