Earthquake Alerts

Special recommendations on CAP for earthquakes

Alerting area

Many of our publishers specify the <area> as a <circle> centered at the earthquake's epicenter. We strongly suggest that you specify a non-zero radius instead of a single point, because Google Public Alerts are shown more broadly to users located inside the <area> than to users outside of the <area>. For example, your system can select a radius from a set of predetermined radii values depending on the earthquake's magnitude or depth. If you must set a zero-radius circle, please note that Google will have to choose a non-zero targeting radius to use instead. Zero-radius circles are considered empty target areas, which Google Public Alerts doesn't support.

Since many earthquakes are centered in remote or offshore locations, we also suggest that you specify the value of the <areaDesc> element in terms of the epicenter's distance and direction from a more populated or better-known area. For example:

<areaDesc>10 km SW of Christchurch</areaDesc>

This makes it easier for users to identify the location of the quake using one or more better-known reference points.

Additional parameters

Please include separate parameters in your CAP for information that you use to help the public understand an earthquake's strength and intensity. This might include the earthquake's magnitude, intensity, depth, or origin time. For example:


   <value>12 km</value>  

Google can then parse some of these structured parameters to construct alert titles or other strings to display on Google Public Alerts. However, it's still a good idea to include the same information in human-readable language in your CAP alert's <description>, as well.

Rich media resources

If you have an intensity shakemap image, epicenter map image, or other rich media resources that you'd like to display with your alert, please use the <resource> element to specify the type and content of the resource file.

Shake intensity

The following semicolon-separated syntax expresses earthquake shake intensities and locations: