AlertMaps are ElarmS' prediction of the coming ground shaking. AlertMaps are updated every second as more information is incorporated into the ElarmS predictions. As time progresses and the ground shaking spreads across a region the initially predictive AlertMaps evolve into a ShakeMap which is a map of the observed peak ground shaking. You can view the AlertMaps as an animation or look at individual frames.

These time histories show the progress of the ElarmS algorithms with time. The "Ground motion" plots show the error in the predicted ground shaking intensity (using the MMI scale), the predicted peak ground acceleration (PGA) and the predicted peak ground velocity (PGV). The "Magnitude" plots show the ElarmS magnitude estimate as a function of time. The "ElarmS magnitude" uses observations of P-wave amplitude and frequency content. The magnitude estimates using just the peak amplitude and just the predominant period are also shown. Finally the "Observations" plot shows the number of vertical channel triggers, the number of P-wave peak amplitudes and predominant periods.