On June 24, Venezuela was struck by two powerful earthquakes—a magnitude 7.2 followed by a 7.5—less than 40 seconds apart. Before the shaking was felt, many Android users' phones in the area started sounding; it was not a call, but Google's earthquake alert. One resident said that seconds after the alarm went off, her house began to sway, and she grabbed her 2-year-old child and family and quickly took shelter beside a pillar. Others posted on X: "My phone went crazy with an alert seconds before the earthquake, thanks to it I rushed into the yard."
I have been following Google's use of global Android devices to detect earthquakes for some time, and today let's talk about this vast spatiotemporal GIS-based earthquake early warning network.
How It Works
When an earthquake occurs, it first emits fast-traveling, relatively less destructive P-waves (primary waves), followed later by more damaging S-waves (secondary waves). The gap between them is often a few seconds to tens of seconds. An Android phone's accelerometer can theoretically detect the subtle ground motion caused by the P-wave.
The process generally works like this:
- After a phone remains stationary for a while, the background service starts monitoring accelerometer data;
- If it detects vibration patterns resembling seismic P- or S-waves, it sends the signal and location to Google’s servers;
- The server aggregates similar signals reported simultaneously by thousands of devices in a region, confirms an earthquake, and estimates its magnitude and epicenter;
- It pushes an early warning via mobile networks to users who may be affected.
Pros and Cons
Compared to traditional seismograph networks, the biggest advantage of this Android-based spatiotemporal seismic network is its low cost. Professional stations require land acquisition, power supply, communications, and maintenance. Some developing countries may lack the financial resources to build a dense monitoring network, but almost everyone has a phone. The feature is built into the system and turned on by default without installing an app. Within a few years of launch, it expanded from a few countries to nearly a hundred. Venezuela is a typical example of such a country, and many benefited from this feature during the recent quakes.
Although the feature is useful, it is far from a replacement for professional seismic stations. The system depends on enough stationary phones reporting simultaneously; in sparsely populated areas or for offshore earthquakes, its effectiveness diminishes. Magnitude estimation also has errors: some people in Venezuela received an estimated M6.2, while the actual mainshock was M7.5. There is also a probability of false alarms. By March 2024, a total of 1,279 alerts had been issued, with 3 false alarms caused by thunderstorms or mass notifications triggering collective phone vibrations—similar to the time when someone pulled a cart of phones on a road and caused Google Maps to show a traffic jam.
The Story Behind It
The key people behind this feature include Google's Android chief software engineer Marc Stogaitis and his team, Professor Richard Allen and Dr. Kong from UC Berkeley, and renowned USGS seismologist Dr. Lucy Jones, who is well known for her public outreach on earthquake risk.
The system first went live in the United States in 2020. Starting in April 2021, warnings generated by the Android crowdsourced network began to be pushed in New Zealand, Greece, and other places. By the end of 2023, it covered 98 countries and regions. In a media interview, Marc Stogaitis said they prioritized deployment in countries with historically high earthquake risk but no mature official early warning system, such as Venezuela. In April this year, during a M6.2 earthquake in Turkey, the system sent the first alert 8 seconds after the quake; users in areas experiencing moderate to strong shaking got anywhere from a few seconds to 20 seconds of warning, and more than 11 million alerts were pushed that day.
Apple's Approach
Apple takes a different approach. Instead of building a global crowdsourced monitoring network using its accelerometers like Google, Apple relies mainly on system-level government alerts and integration with official data sources. In Japan, iPhones can receive the Japan Meteorological Agency's Earthquake Early Warning, but this is delivered through local carriers' cell broadcast. In some US states, iPhones connect to professional warning networks such as ShakeAlert. Starting with iOS 26.2, Apple introduced Enhanced Safety Alerts, with earthquakes and imminent threats delivered at two levels: Awareness and Action. iPhones can also anonymously forward alerts to nearby Apple devices. This currently mainly covers the United States and China's Taiwan region.
Mature Warning Systems in Other Countries
After discussing Google, let's briefly look at mature earthquake early warning systems elsewhere, using Japan and China as examples.
Japan was one of the first countries to deploy large-scale commercial earthquake early warning. At its core is a dense network of professional seismometers. The public-facing system is the Japan Meteorological Agency's Earthquake Early Warning, integrated with the J-ALERT nationwide instantaneous warning system. Alerts go out simultaneously via cell broadcast, television, radio, and outdoor speakers, sharing the same infrastructure as air defense and tsunami warnings. The Shinkansen bullet train has a dedicated UrEDAS braking system that can slow trains as soon as shaking is detected. During the 2011 Tohoku earthquake, many areas in Tokyo gained roughly 80 seconds of warning. Japan has had false alarms, but decades of operational experience, legal safeguards, and nationwide disaster preparedness education make it one of the world’s most advanced earthquake early warning countries.
China has launched the National Earthquake Intensity Rapid Reporting and Early Warning Project (National Earthquake Early Warning Project). Construction began in 2018 and was accepted upon completion in July 2024. It has established a nationwide earthquake early warning network, with an average first alert time of about 7 seconds in key warning areas and 10–30 seconds in general warning areas. Unlike Google's phone-only approach, China uses a full chain of station observation, data processing, and information dissemination. The China Earthquake Networks Center, provincial and municipal earthquake bureaus, emergency broadcasting, television, mobile apps, and WeChat mini programs are all integrated. Manufacturers such as Huawei, Xiaomi, OPPO, and vivo have also connected to the system.
P.S. Currently in mainland China, iPhones do not have the national earthquake early warning system built in at the system level, so they cannot receive system-level alert pop-ups like some domestic Android phones. The China Earthquake Administration has been actively promoting technical cooperation to bring earthquake early warning to iOS, but no specific timeline has been announced. If you are an iPhone user, it is recommended to download the China Earthquake Early Warning app or follow the "China Earthquake Networks" WeChat warning service and enable critical alert permissions.
Final Thoughts
I believe Google's alert technology and traditional station networks are not mutually exclusive. Where stations exist, Google also integrates official data; it relies on phones mainly where there is no network. Overall, having an additional channel and tool is better. However, I imagine many people share my question: is the real-time collection of this data safe? Indeed, one reason many countries have not enabled this feature is privacy laws and regulations. The debate over whether to trade some privacy for public benefit has not stopped either.
Finally, I'd like to ask you: have you ever received an earthquake alert? Was it from the government, a phone manufacturer, or Google? Feel free to share in the comments. If you experienced it firsthand in Venezuela, Turkey, the Philippines, or elsewhere, you're welcome to share your impressions.