Earthquake Early Warning
Earthquake early warning (EEW) detects an earthquake after it begins and attempts to notify locations before damaging shaking reaches them. It is not earthquake prediction.
Why warning can be possible
Seismic waves travel through the Earth much more slowly than electronic messages. A system can detect early arrivals, estimate the event and expected shaking, and distribute a message while stronger waves are still traveling toward more distant locations.
Earthquake begins
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Stations detect initial motion
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Processing associates observations and estimates the event
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Expected shaking is evaluated for target locations
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Alerts are distributed
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Strong shaking reaches locations that are far enough away
Every step consumes time. Warning time depends on the earthquake, station geometry, detection thresholds, processing, communications, alert policy, and recipient's distance from the source. A fixed table of warning time by epicentral distance is misleading because depth, wave speeds, network layout, and latency vary.
Blind zone
Locations close to the source can experience strong shaking before the system has enough observations to issue a useful alert. No network density or communications technology eliminates this blind zone completely.
Initial estimates change
The earliest data represent only the beginning of a rupture. Automated estimates can change as:
- More stations detect the event
- The rupture grows
- Noisy or incorrect picks are rejected
- Magnitude calculations receive longer waveform windows
Alert design must account for late, missed, false, and updated messages. Automated actions should be based on an engineering risk assessment, not only a magnitude threshold.
Components of an EEW service
Detection network
Stations require suitable geometry, low enough noise, accurate timing, reliable telemetry, and known metadata.
Processing
The system identifies candidate arrivals, associates stations, estimates source parameters, predicts expected shaking, and decides whether alert criteria are met.
Alert delivery
Messages may be delivered through public warning channels, applications, sirens, or direct machine interfaces. Delivery latency and availability must be measured end to end.
Prepared response
A warning is useful only when recipients know what to do. Procedures, training, accessibility, testing, and fallback behavior are part of the system.
Appropriate actions
Depending on jurisdiction and engineering review, warnings can support actions such as prompting people to Drop, Cover, and Hold On or placing controlled systems into a safer state. Automatic control of trains, utilities, industrial processes, elevators, or medical systems requires specialist design, fail-safe behavior, and approval from the responsible operators.
Grillo Earthquake Monitoring
Grillo sensors can provide observations to a network. The Platform's Earthquake Monitoring module, powered by SISTEM, can produce automated event information for configured deployments. The current Platform Live page is a simulation, not an operational public-warning feed. Alert delivery and external integrations are deployment-specific and are not self-service controls in the current Platform UI.
Do not present a sensor installation as an operational EEW system until the complete detection, alerting, governance, and response chain has been validated.