One of the recurrent questions is:why doesn’t the seismic alert sound in CDMX micro earthquakes? Here we bring you the answer.
Let’s start from the general. The seismic alert is a system whose main objective is to alert the population about the imminent arrival of an earthquake. The idea is to provide certain seconds of advantage so that citizens can evacuate or move to places of lower risk.
As detailed in the Mexican Seismic Alert System website, the time of opportunity offered is from 20 to 120 seconds depending “on the distance between the site where the earthquake starts and the city to be alerted”. Now, how does it do this?
The system has 96 sensors installed in different states of the country: Guerrero, Oaxaca, Puebla, Jalisco, Colima and Michoacán. When an earthquake occurs, each sensor collects certain information and the possible magnitude of the tremor. Afterwards, it is analyzed whether the alert is activated or not.
It is even detailed that the alert will be activated depending on several factors, such as the estimated energy of the earthquake and the distance to the city to be alerted, among others.
What happens with the seismic alert in CDMX micro-earthquakes?
In the case of micro-earthquakes in CDMX the situation is different. In a UNAM bulletin, the doctor of the Institute of Geophysics, Luis Antonio Dominguez Ramirez, details that the seismic alert does not sound in these cases for two reasons:
- The magnitude of the micro-earthquakes is very small.
- The seismic alert detects earthquakes in the most active seismic region (formed by the states mentioned above).
In addition, SASSLA explains that, as the microseismic earthquakes occur right in CDMX (below us), it is not possible to issue any alert. Furthermore, if there is one, it would not give any time advantage.
Although Mexico is a highly seismic country, it is not possible to predict an earthquake, so it is always necessary to be prepared.