The challenge of estimating an earthquake’s power

One of the trickiest parts of an EEW system is estimating the magnitude of an earthquake in real-time. The magnitude tells us how big the earthquake is, which in turn determines how far the shaking will travel and who needs to be alerted. Getting this right is crucial — underestimate, and you might not warn people in danger; overestimate, and you risk sending out false alarms that erode public trust.

The challenge lies in the trade-off between speed and accuracy. The first few seconds of an earthquake provide limited data, but every second you wait to issue an alert is a second less of warning for those in the path of the shaking.

Over the last three years, we’ve continuously improved our magnitude estimation. The median absolute error of our first magnitude estimate has dropped from 0.50 to just 0.25. When we compare our system to established, traditional seismic networks, our accuracy is similar, and in some cases, even better.