Earthquake-sensing cellphones are here: Simple sensors connect them to a global network of earthquake forecasters

Fifty years since the first mobile phone communication, The technology we all now carry in our pockets is helping create the world’s largest earthquake detection system, the BBC reports in a comprehensive report titled How does an everyday item predict earthquakes?

On October 25, 2022, a 5.1-magnitude earthquake struck the Bay Area of ​​California.

Fortunately, it was nothing more than a violent tremor, but the USGS was overwhelmed by reports from residents across the region.

No damage was reported, but the quake was significant in another way — many people in the area got alerts on their phones before the shaking started.

• More importantly, many of these phones also helped detect earthquakes.

Early warning and prediction through simple Android sensors

Google is working with the USGS and academics at several universities in California to develop an early warning system that notifies users seconds before tremors are coming.

It’s a small warning message for extremes, but a few seconds can give enough time to get under a table or desk. It may also be enough time to slow trains, prevent planes from taking off or landing, and prevent cars from entering bridges or tunnels.

• Therefore, this system is more likely to save lives when stronger earthquakes occur.

It uses data from two sources.

Initially, the system relied on a network of 700 seismometers—devices that detect ground vibrations—installed across the state by seismologists from the USGS, Caltech, UC Berkeley, and state government. (Seismometers in two other US states – Oregon and Washington – also feed into the system known as shakeAlert.)

• But Google has also built the world’s largest earthquake detection network with phones owned by members of the public.

Most of Google’s Android smartphones have built-in acceleration – The circuit that detects when the phone is moved. They’re most commonly used to tell a phone to reorient its screen from portrait to landscape when it’s tilted, for example, and also help provide step count information to Google’s built-in fitness tracker.

• But the sensors are surprisingly sensitive and can also act as a mini-seismometer.

Google has introduced a feature that allows users to give their phones permission to automatically send data to Android’s earthquake alert system if their device receives vibrations characteristic of the main (P) waves of an earthquake.

By integrating data from thousands or even millions of other phones, the system can determine if and where an earthquake is occurring. It can then send alerts to phones in the area where seismic waves are likely to hit, giving an early warning.

• And because radio signals travel faster than seismic waves, alerts can reach areas far from the epicenter of the earthquake before shaking begins.

The speed of light versus the speed of an earthquake

Mark Stogaits, Android software engineer put it this way:

“We are basically traveling at the speed of light (which is the speed at which signals travel from a phone) versus the speed of an earthquake. And lucky for us, the speed of light is much faster!».

Since most data comes from many signals, the technology opens up the possibility of monitoring earthquakes in areas without extensive networks of accurate seismographs. This means that it increases the ability to provide earthquake alerts even in the most remote and poor parts of the world.

In October 2022, Google engineers watched phones across the San Francisco Bay Area light up with earthquake detection data as seismic waves traveled from the epicenter.

Earthquake in the San Francisco Bay Area today. Yellow/red represents the vibration of Android phones which act as seismometers. Circles are our inferred estimate of P&S waves. Earthquake alerts are sent instantly to surrounding phones before the waves hit pic.twitter.com/8pumt19ReI

– Dave Burke (@davey_burke) October 26, 2022

The system now gets these vibrations regularly. Recently, on the evening of April 4, 2023, a 4.5-magnitude earthquake that occurred near Tres Pinos, California was recorded by the system. shake alert, Sending messages on mobile phones about uses in the area.

Earthquakes are a common occurrence in California, with up to 100 small earthquakes occurring each day. Most of them are too young to feel it. However, there are usually several larger earthquakes in California annually, with a magnitude of about 15-20 greater than a magnitude of 4.0.

• More broadly, of the estimated 16 billion mobile phones in use worldwide, more than three billion are powered by Android, and the earthquake alert system is now available in more than 90 earthquake-prone countries.

But the system does have its limitations, particularly in remote areas where there are few phone users and in marine earthquakes that can trigger tsunamis.

And while it can help produce warnings a few seconds in advance, the science of predicting earthquakes before they happen remains as mysterious as ever.

with information from BBC

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