The technology we carry about in our pockets is assisting in the creation
of the largest earthquake detection system in the world, fifty years after
the first mobile phone call.
California's Bay Area
was
shaken
by a 5.1-magnitude earthquake on October 25, 2022. Fortunately, it wasn't a
particularly strong tremor, but reports from locals all across the area who
had felt it poured into the United States Geological Survey (USGS). Although
there were no reports of damage, the earthquake was notable in another
aspect since many locals got notifications on their phones before the
shaking began.
More importantly, many of these phones contributed to the earthquake's
first detection.
In order to create an
early warning system
that informs users of earthquakes just a few seconds before they occur,
Google has been collaborating with USGS and researchers at a number of
Californian colleges. Although the window of warning is small, a few seconds
can provide you enough time to find cover behind a desk or table.
Additionally, it may be long enough to slow down trains, halt planes from
taking off or landing, and prevent vehicles from passing through bridges or
tunnels. As a result, when greater earthquakes strike, this technology may
save lives.
Two sources of data are used. Seismologists from the USGS, the California
Institute of Technology, the University of California Berkeley, and the
state government constructed a network of 700 seismometers—devices that
detect ground tremors—across the state. (Seismometers in two other US states
– Oregon and Washington – also feed into the system, known as ShakeAlert.)
However, Google has also been using publicly available smartphones to build
the greatest earthquake detection network in the world.
The hardware that senses when a phone is being moved, known as an
accelerometer, is built into the majority of smartphones running Google's
Android operating system. These are often used to instruct the phone to
switch from portrait to landscape mode when it is tilted, for example, and
also assist in giving Google's built-in fitness tracker information about
the number of steps taken.
The sensors, however,
may also function
as a miniature seismometer and are remarkably sensitive.
If a user's phone detects vibrations that are indicative of the Primary (P)
waves of an earthquake, Google has implemented a feature that enables
automatic data transmission to the
Android Earthquake Alerts System. The technology can determine whether and where an earthquake is occurring
by merging data from hundreds or even millions of other phones. In order to
provide an early warning, it may then send warnings to phones in the
vicinity of where the seismic waves are anticipated to land.
Additionally, because radio messages move more quickly than seismic waves,
notifications can reach distant locations before the shaking begins.
We're literally competing the speed of light (about the speed at which
phone signals travel) against the speed of an earthquake, said Marc
Stogaitis, an Android software engineer. Fortunately, the speed of light is
considerably faster for humans.
The technique makes it possible to watch for earthquakes in locations
without vast networks of expensive seismometers because the majority of the
data is generated by the public. It increases the likelihood of sending
earthquake notifications to even more isolated and underdeveloped parts of
the planet.
As the seismic waves propagated outwards from the epicentre in October
2022, Google engineers observed phones
lighting up with earthquake detection data
all throughout the San Francisco Bay Area.
These vibrations are frequently picked up by the present system. The
ShakeAlert system most recently detected
an earthquake of
magnitude 4.5
on the afternoon of April 4, 2023, close to Tres Pinos, California, and sent
alerts to nearby users' mobile phones. In California, where there are
up to 100 little quakes every day, earthquakes are frequent occurrences. They are typically too tiny to
feel. However, California experiences many earthquakes of greater magnitude
annually—roughly 15-20 are greater than magnitude 4.0.
The Earthquake Alerts System is already available in more than 90 countries
that are highly vulnerable to earthquakes, and of the estimated
16 billion mobile phones in use worldwide, more than
three billion run Android.
However, the system has its drawbacks, especially in distant locations with
few phone users and when quakes occur offshore where they might cause
tsunamis. And while technology can assist in sending out signals a few
seconds beforehand, the science of accurately forecasting earthquakes
remains as elusive as ever.
