VOA慢速英语2020--谷歌现实通过安卓系统手机追踪地震警报（在线收听）

Google has launched a communications system that uses the company's Android phones to detect earthquakes. It aims to provide timely information about earthquakes to phones that run the mobile operating system.

The new warning system has already been tested in California, which has more damaging quakes than any other part of the United States.

To develop the system, the company worked with the U.S. Geological Survey - USGS - a federal agency that uses seismographic equipment to measure earthquake activity.

Technology for predicting earthquakes does not yet exist. But the USGS says it does have equipment to predict seismic activity near a quake. This means it is possible to warn people in areas where such activity is expected. People could then get several seconds or perhaps up to a minute of warning before a quake strikes.

The USGS joined several university partners in developing the new warning system, called ShakeAlert.

Scientists say the Earth's outermost surface is made up of large tectonic plates. As many as 20 tectonic plates cover the planet. They move slowly, sometimes sliding under one another. When that happens, earthquakes can take place. This sudden release of energy creates different kinds of waves that cause the ground to move.

The USGS says the purpose of ShakeAlert is to identify the first energy to be released in an earthquake. This first sign of a quake is known as primary wave energy.

When sensors identify this primary wave, Android phones immediately report the movement to a processing center, which then estimates the quake's size and intensity. The center uses this data to create a message to warn people using the phones to take action, such as dropping to the ground or taking cover.

The USGS says studies in California and two other states have shown that the system could provide warning times "from a few seconds to tens of seconds." In addition to warning individuals, such alerts could be used to slow trains, airplanes moving on the ground or prevent cars from entering bridges or tunnels.

These messages could also be sent to businesses so their workers can close down gas lines, elevators or other equipment before the shaking begins.

The USGS system in California has more than 700 sensors, called seismometers, to measure earthquakes. But creating equipment-based systems around the world would be difficult.

As a possible solution, Google launched its own earthquake alert system for Android users worldwide. Google says the system turns its phones into small seismometers. Millions of devices with the technology "form the world's largest earthquake detection network," the company said on its website.

More than 2 billion devices use the Android operating system.

Google says all smartphones have built-in accelerometers to measure direction and force of motion. These sensors are mainly used to show how the phone is being held.

If the phone identifies something that might be an earthquake, it sends a signal with data about where the shaking happened to a central computer server. The server then combines the data with information from other devices to decide whether an earthquake is, in fact, happening.

Google says the process "is racing the speed of light against the speed of an earthquake." It adds: "Lucky for us, the speed of light is much faster!"

No extra computer software is needed to run the system on Android devices. Alerts will be sent for earthquakes with a strength of 4.5 or greater. Users will receive a sound alert and warning on the screen telling them to immediately drop to the floor and seek cover.

Google says the data will also be used to provide fast and accurate information on earthquakes through its search engine. When a user searches "earthquake" or "earthquake near me" on Google, the latest information will be shown, along with "helpful resources" on what to do after an earthquake, the company said.

Google said it plans to add the service to Android users in other states and countries over the next year.

I'm Bryan Lynn.

Words in This Story

detect – v. discover or notice something

mobile – adj. able to be moved freely or easily

seismographic – adj. relating to equipment used to detect and measure earthquakes

tectonic plate – n. one of the parts of the earth's surface that move in relation to each other

primary – adj. earliest in time or order

tunnel – n. long passage that runs underground or through a mountain

elevator – n. a device that moves people and things up and down inside a building

screen – n. the flat panel area on an electronic device

accurate – adj. correct or exact