I.Earthquake alert basics

As electric waves are faster than seismic waves, when an earthquake takes place, by deploying intensive earthquake alert monitors in earthquake zones, earthquake alerts can be sent to users by methods such as phones and emergency broadcasts so that they can take cover immediately.

II.Detailed description of Earthquake alert

1. Magnitude: a measure of the amplitude of the seismic waves generated by a hypocenter. One earthquake has only one magnitude.
2. Intensity: a measure of the impact and damage caused by an earthquake to your region. Intensity is related to the earthquake magnitude, focal depth, and your distance from the hypocenter. The intensity decreases as the distance from the hypocenter increases.
3. Alert time: the time at which destructive seismic waves are going to arrive.

III.What do I do if I receive an earthquake alert?

1. Basic safety principles
Remain calm, do not jump from buildings, and do not use elevators
2. Safety tips

IV.Why can't I receive an earthquake alert?

Even if the Earthquake alert service is enabled, earthquake alerts won't be received in any of the following cases:
1. The Earthquake alert service is not currently supported in your region.
2. Your device has no internet connection or has a poor network connection.
3. The alert distribution channel cannot keep smooth.
4. Auto-location is not enabled in Weather or your city is not added to the list of cities.
5. The estimated earthquake intensity of this region is lower than Scale II (Slightly Felt).

V.Alert blind zone

The earthquake alert blind zone is an area where the destructive seismic waves have already caused building damage and reached the location of the affected people by the time earthquake alert information is sent to them. The earthquake alert blind zone is often the area with the maximum earthquake damage, that is, the meizoseismal area. Generally speaking, the earthquake alert system is only effective for areas within the range of 50 to 200 kilometers from the epicenter. For areas within 50 kilometers, the alert time is too short to respond, which is the so-called earthquake alert blind zone.
The inherent shortcoming of earthquake alerts is that there are unrealizable alert blind zones, which can only play a role in disaster reduction in specific conditions and specific areas.