PAGER Frequently Asked Questions

Q: Is there a concise, printable version of PAGER results?

A: Yes, the "onePAGER" contains the all the major elements produced by PAGER in a Portable Document Format (PDF) file. It is available from the download tab of the PAGER webpages for a specific earthquake. An example onePAGER can be found here and a description of its content can be found here.

Q: Which earthquakes are analyzed by the PAGER system?

A: PAGER population exposure estimates and supporting products are generated for all earthquakes magnitude 5.5 or greater worldwide. Additionally, PAGER results are generated for smaller earthquakes, greater than about magnitude 3.5, in the contiguous United States, Hawaii, and Anchorage region.

Q: How long after the earthquake are the PAGER results available?

A: For earthquakes larger than magnitude 5.5, PAGER estimates are generally available on the Internet within 30 minutes of the earthquake's occurrence and are updated as more information becomes available. However, information on the extent of shaking will be uncertain in the minutes and hours following an earthquake and typically improves as additional sensor data and reported intensities are acquired and incorporated into models of the earthquake's source. Users of PAGER exposure estimates should account for uncertainty and always seek the most current PAGER release for any earthquake.

Q: What is the modified Mercalli Intensity scale and how is it different from magnitude?

A: The effect of an earthquake on the Earth's surface is called intensity. Intensity describes the severity of an earthquake in terms of its effect on humans and structures and is a rough measure of the amount of shaking at a given location. Unlike earthquake magnitude, intensity varies with distance from the fault. Although numerous intensity scales have been developed to evaluate the effects of earthquakes, the one currently used in the United States is the Modified Mercalli Intensity (MMI) Scale.

Q: How are the estimated ground motion intensities calculated?

A: The ground motion intensities are calculated using the USGS ShakeMap system. A ShakeMap is a representation of ground shaking produced by an earthquake. The ground shaking intensity at sites throughout the region depends on the earthquake's magnitude, the geometry and size of the ruptured fault, distance from the earthquake fault, the rock and soil conditions at sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the Earth's crust.

Q: Why doesn't PAGER estimate loss of life or property?

A: Estimating casualties and property damage requires information beyond the number of people exposed to shaking. Loss estimates are currently produced using sophisticated methodologies and software including FEMA's HAZUS. These methodologies require databases of building inventories and estimates of building strength. No such database exists on a global scale so the USGS is conducting research and tests on empirically calibrated loss models and hybrid models that use available inventory data. Output from these models will be incorporated into PAGER results.

Q: Does PAGER provide tsunami warnings?

A: PAGER and the USGS do *not* provide tsunami warnings. Tsunami warnings are issued by the National Oceanic and Atmospheric Administration (NOAA).

Q: Are PAGER results available by e-mail?

A: 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). This service lets you sign up for alerts from custom geographic regions and magnitude ranges. PAGER results for a specific earthquake can be found by following the link provided in the ENS message and looking under the "maps tab". There is up to a 5 minute delay from the time the initial earthquake solution is posted to the web and the PAGER results are available.