The northeastern region of the country was hit by an earthquake at 4:41 PM today, 14th September 2025. The epicentre of the earthquake was near Udalguri town in Assam, the district headquarters of Udalguri district bordering Bhutan and Arunachal Pradesh.
The magnitude of the earthquake has been reported as 5.8 on the Richter scale by the National Centre of Seismology. However, the USGS has recorded the magnitude as 5.9, which is actually twice the magnitude of 5.8 as it is a logarithmic scale.
The tremors lasted for a long duration, spreading panic among people in the affected areas. There are no reports of casualties or damage to property so far.
Notably, as soon as the earthquake hit and everything started shaking, mobile phones instantly displayed an earthquake alert. The alert called ‘Android Earthquake Alerts System’ was displayed on the mobile devices with an alarm tone. In some cases, the tremors were felt after the alert was received.
The Android Earthquake Alerts System is Google’s built-in feature on Android phones that detects earthquakes and warns users seconds before the shaking begins. It works by combining smartphone sensors with seismological data. Here’s how it functions step by step:
This system uses the accelerometer present in the Android phones to detect earthquake in real time, and display an alert. As per Google, when an Android phone “detects the initial, faster-moving P-wave of an earthquake, it sends a signal to our earthquake detection server, along with a coarse location of where the shaking occurred.”
P waves travel faster than other seismic waves and therefore they are the first to arrive in case of an earthquake. The censor in ordinary Android smartphones now can detect this P waves, which is used to send the alert people.
However, a single phone detecting vibration isn’t enough, as it could just be someone dropping it. When many nearby phones detect similar shaking at the same time, Google’s servers treat it as a likely earthquake.
The system then quickly analyses data from many phones and estimate its location and magnitude. The system works in lightning speed, resulting in issuing alert almost immediately when an earthquake is detected.
A global Android smartphone-based earthquake detection and early warning system can detect seismic activity in real time and deliver life-saving alerts with effectiveness rivaling that of traditional seismic networks, according to a new study in Science.
— Science Magazine (@ScienceMagazine) July 24, 2025
?:… pic.twitter.com/7aYHAEs0fl
This makes the system the world’s largest earthquake detection network, since millions of Android phones act as mini-seismometers.
Today the system’s efficacy was tested and proved in real time in Assam’s Udalguri, as it sent alerts to phones located in the affected zone with amazing speed and accuracy, as the earthquake and the alert started almost at the same time.
The big black scree of the alert asked people to Drop, Cover and Hold for safety, and had an option to silence the alarm sound. The alert even included an estimate of the magnitude, saying it was 5.7, very close to actual magnitude.
The alert included additional screens, which included a map of the epicentre of the earthquake, and several safety tips. It warned that aftershocks are common after earthquakes.
That was accurate from Android..20 seconds before the tremor it alerted..how tf did it work ? pic.twitter.com/u8NIDT0YmR
— Ambarish (@Dinku_cfc) September 14, 2025
We have an earthquake alert system in Android now? pic.twitter.com/7el1JRbxGd
— Abbash Ali (@abbashali01) September 14, 2025
Notably, while people living near the epicentre received the above alert message, people in the periphery of the zone received a different alert, saying ‘Earthquake Nearby’.
People on social media posted screenshots, wondering how the system even worked as the alert came before the tremors in places some distance away from the epicentre.
