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NASA's Space Place

Measuring Earthquakes Faster

Katie McKissick
National Aeronautics and Space Administration

Earthquakes can be serious, scary events. The ground shakes and rolls. Things can fly off shelves, and buildings can collapse. We can do a lot to prepare for earthquakes before they happen. But what can we do to prepare for what happens after them?

When an earthquake occurs, it’s important to know the location, depth, and overall strength of the earthquake. People use this information to respond to the earthquake and help people.

To figure this out, we use sensors on the ground that measure vibrations. But with really big earthquakes, it gets harder to tell the size from the vibrations alone. The sensors also take a long time to send the information to scientists. Measuring earthquakes this way can take up to 25 minutes. That’s a lot of time when a big earthquake strikes and people need help.

It’s great that we can measure the amount of shaking, but we need more information. What if we knew just how much the ground moved? Sometimes this is dramatic. Roads can be cut in half. Hillsides can rise or fall. But that can take a while to measure. Wouldn’t it be great if we could know right away?

This sounds like a job for GPS. GPS stands for global positioning system. This is the technology that uses satellites and ground stations to locate things all over the planet. It’s the reason our phones can give us direction to the nearest pizza place or tell us the local weather. It knows where you are.

GPS could also tell us how much an earthquake station moved during an earthquake. But the GPS that we have in our cars and smart phones can’t tell if something just moves a few inches or feet. It knows the location of things based on how long a satellite message takes to get to it, but things like clouds can slow down the message. This means that GPS by itself couldn’t tell if something moved just a little bit.

But with some help from NASA, it can!

NASA scientists along with researchers from the Scripps Institution of Oceanography updated some GPS stations in Southern California. They now have sensors that monitor for earthquakes and collect GPS information, but they also take measurements of pressure, temperature, and vibrations. The weather data helps make the GPS information more accurate. Now we can tell how much that GPS station has moved when an earthquake happens. Some of these GPS earthquake stations are being installed on top of important places like hospitals, bridges, and skyscrapers. That way we know if they were moved or got damaged in the earthquake.

And it all happens faster, too. After an earthquake, scientists could know in minutes exactly where the earthquake happened and how serious it was. That means they can get help to people who need it faster than ever before. The NASA scientists are also working on an early warning system for the west coast that will give you a 1-2 minute warning before you feel the earthquake shaking. That will give you time to take cover.

Want to know more about how GPS works? Visit spaceplace.nasa.gov/gps.

Principal Investigator Dr. Yehuda Bock’s colleagues (background) with a typical GPS station in southern California. They have installed inexpensive sensors that monitor for earthquakes while collecting GPS, pressure, temperature and seismic data in real-time at 25 stations, as part of the natural hazards warning systems being jointly developed by Scripps Institution of Oceanography and NASA Jet Propulsion Laboratory. Credits: Marc Tule


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