On Tuesday morning local time, active Android phones in the San Francisco Bay Area displayed a warning on their screens: waves from a magnitude 4.8 earthquake were on their way. Some of the messages said: “You may have felt a tremor.” More than one million users of Android phones saw the warning and wrote WiredFor some of them, the warning was displayed a few seconds before the earthquake.
Mark Stugaitis, the leader of the Android earthquake warning system project, says that this is not the first time that Android phones show such a warning to users. However, since the San Francisco Bay Area has a large population, the number of phones receiving earthquake alerts was high enough to attract public attention.
Earthquake comes without warning and does not protect. When an earthquake occurs, people are caught by surprise and do not have enough time to take shelter, which makes them more likely to be injured. Systems such as the one implemented in Android try to notify the earthquake a few seconds earlier so that people can take shelter.
Robert DeGroot, a member of the team developing the ShakeAlert warning system (a project managed by the US Geological Survey to detect the first signs of an earthquake), says: “One of our goals is to create an industry for earthquake early warning systems. “We’re doing things that we’ve never really thought of before.”
Experts say that the technology used in Android is not a system to “predict” earthquakes. Earthquakes cannot be predicted by any tool, and the US Geological Survey has said in previous statements that it is very likely that it will not be able to design a system to predict earthquakes “in the near future.”
Android’s alert system cannot “predict” an earthquake
Android’s alarm system can notify a person of an earthquake before they feel it. Specialists hope that one day it will be possible to design a system that will notify the user of the occurrence of an earthquake much earlier.
Google says the alert that appeared on Android phones last Tuesday was the result of a partnership with ShakeAlert. The ShakeAlert Institute detects the first signs of an earthquake and makes relevant data available to government agencies and various companies. Google has taken important steps to make the notifications from the ShakeAlert system much more widely available.
Google initially integrated the ShakeAlert alert with its own system so that Android phone users can see the ShakeAlert notification through their phone. Thanks to this cooperation, the display of notifications is not dependent on downloading a separate application and everything is done on the basis of the operating system.
In the early stages, an earthquake sends soft seismic waves called P waves through the ground. Not everyone in the earthquake area will feel P waves; But a network of 1,300 advanced USGS sensors can detect P waves.
When the four sensors react to receiving a wave simultaneously, they send an alert to the data processing center. If the data matches some predefined criteria, the system ShakeAlert detects that even more powerful S waves are likely on the way.
S-waves are the seismic waves that cause damage on the surface of the earth and are felt by people. After these steps, early warning systems such as Google’s system, MyShake app, government agencies such as the Federal Emergency Management Agency or transportation systems interpret the data and start sending alerts.
Early warning systems also have limitations. S waves travel at high speed. In other words, the closer one is to the epicenter, the less likely one is to receive a warning before an earthquake occurs. The USGS sensors are very expensive and are strategically placed in various areas of the West Coast of the United States. The organization says it will increase the number of sensors to 1,675 by 2025.
Earthquake early warning systems face limitations
Additionally, earthquake magnitude measurements that are collected very quickly are preliminary data. Tuesday’s warning announced the occurrence of a 4.8-magnitude earthquake; But later it was announced that the San Francisco Bay earthquake had a magnitude of 5.1.
Google says it has turned every user’s phone into a miniature earthquake detection sensor. All modern phones have accelerometer sensors and these sensors can receive earthquake signals. If an earthquake is detected by the accelerometer sensor, the Android phone sends a message with approximate location data (such as the city where the device is located) to a specific server. By checking various data, the server detects in which region an earthquake has occurred and then sends relevant warnings.
Mark Stugaitis says that smartphones can only detect seismic waves when they are connected to a charger and their screens are locked. This will prevent sudden movements of the phone in the pocket or bag from being detected as an earthquake wave. The experts’ long-term goal is to increase the speed of sending earthquake warnings: “We try to shorten as much as possible the time interval between the occurrence of an earthquake by detecting and sending a corresponding warning.”
Equipping smartphones with a system to detect earthquake signals is a cheaper and faster solution than placing large sensors several meters deep underground. However, the phone-based system requires people to be near the location of the earthquake, and such conditions do not occur in all earthquakes. However, all the aforementioned sensors, whether large underground sensors or smartphone sensors, have led to the production of new and unprecedented systems so that people have a small chance to take shelter against the dangers of earthquakes.