PAGER

PAGER stands for the Prompt Assessment of Global Earthqu
Currently, PAGER results are not directly available to the public through e-mail. However, users can sign up for earthquake alerts through the USGS Earthquake Notification Service (ENS).
It is practically impossible to be 100% positive about the exact numbers. For instance, there are still conflicting reports about the death toll and economic loss for the Haitian earthquake.  Hence, the loss models are based on uncertain loss data.
Over the past 38 years there would have been approx. 17,792 green, 568 yellow, 52 orange, and 49 red alerts. This frequency equates to approximately 15 yellow, 1-2 orange, and 1-2 red alerts per year.
Since the information PAGER delivers is a fundamental improvement over simply providing a magnitude and location, or even a ShakeMap, many users have already adopted PAGER results. 
The ground motion intensities are calculated using the USGS ShakeMap system.
In general, the shaking-related impact of an earthquake is controlled by the distribution and severity of shaking, the population exposed to each shaking intensity level, and how vulnerable that population is to building damage at each intensity level.