Here’s how your Android phone alerts you of an earthquake

Many Android phone users who were in Dhaka, Chattogram and nearby districts reported receiving an alert on their phone a few seconds before they felt the earthquake today at 9:35am. 

Sohel Rana, a Facebook user from Dhaka, wrote that he felt the earthquake today (2 December) within two seconds of receiving an alert on his Android phone that said there had been an earthquake "45.8 miles away", followed by some safety tips.

Mahbubur Rahman, a private job holder, also echoed the same. 

"I felt the tremor after only a second of receiving the alert on my phone," he said. 

With the number of screenshots uploaded on social media after the earthquake, it was inevitable that the primary source of news regarding this earthquake was the Android Earthquake Alerts System. 

The warnings, in fact, reached the users even before they physically felt the tremor.

5.5 magnitude earthquake jolts Dhaka, parts of country

Earthquakes happen daily around the world and are considered one of the most unpredictable natural calamities. 

An earthquake is mostly a natural phenomenon that occurs when there is a sudden release of energy in the Earth's crust, creating seismic waves. 

This release of energy usually happens due to the movement of tectonic plates, the large slabs of rock that make up the Earth's surface. 

What we feel during an earthquake is the vibration caused by the movement of the tectonic plates. 

But can you 'predict' an earthquake? 

The United States Geological Survey (USGS) says, "No". 

"Neither the USGS nor any other scientists have ever predicted a major earthquake," it says. 

It goes a step further to say that they do not know how to predict an earthquake, and do not expect to know at any time in the foreseeable future. 

You can only say that there has been an earthquake after the vibration caused by the movement of tectonic plates is felt on the surface, and that's where the Android Earthquake Alerts System comes into play. 

All modern smartphones contain tiny accelerometers that can sense vibrations and speed, signals that indicate an earthquake might be happening. When one of the Android phones with the Earthquake Alerts System enabled, detects such vibration, it sends the info of that tremor with the exact location to Google's earthquake detection server. 

This earthquake server then combines all information it received from many phones to determine if an earthquake is happening and alerts all the users who live in the areas where the tremor is (in many cases, will be) felt.

With this, Google basically turned over 2 billion Android phones currently in use around the world into mini-seismometers to create the world's largest earthquake detection network. 

The most brilliant part about the system is its speed. Google is basically processing all the data and sending the final alerts faster than the earthquake waves reaching you. 

See the Android Earthquake Alerts System in action. 

Do keep in mind that the Android Earthquake Alerts System is neither a prediction nor a forecast. It is an alert. 

According to USGS, early warning systems (the one Android has) use earthquake science and the technology of monitoring systems to alert devices and people when shaking waves generated by an earthquake are expected to arrive at their location.

"The seconds to tens of seconds of advance warning can allow people and systems to take action to protect life and property from destructive shaking," says USGS.