Gravity Signals Traveling At The Speed Of Light Could Warn Of Big Earthquakes


A new study hypothesizes that monitoring shifts in gravitational waves could help detect exceptionally large earthquakes. How can this help public authorities respond to earthquakes better?

The Trouble With Earthquakes

Earthquakes are one of the most destructive natural disasters that can occur. Compared to other destructive forces like hurricanes and tornadoes, earthquakes cannot be accurately predicted until the damage has already been done. This leaves both the authorities and the public almost no time to prepare, with relief operations as the only course of action to take after the earthquake has already struck.

However, a new study published in the journal Science details a possible method for detecting big earthquakes by measuring the gravitational signals that travel along the ground. Compared to measuring seismic waves, gravitational signals travel at "the speed of light."

Gravitational Waves To Measure Earthquake Strength

In 2011, the seismometers in China and South Korea detected the gravity signals immediately after the 9.1 magnitude earthquake that rocked Japan. The signals came over a minute before the seismic data was picked up. What's more, because they were monitoring the seismic waves and not the gravity waves, it took the US Geological Survey about 40 minutes to determine an estimate of the earthquake's magnitude while the Japan Meteorological Society took 3 hours.

The current study suggests that had they been looking at gravitational waves instead of seismic waves, they would have determined the earthquake's strength much faster, and could have alerted the authorities as to the kind of emergency response to take.

However, the problem with gravitational waves is that they are weaker than seismic waves. They are detectable in major earthquakes of magnitude 8.5 or even higher, which is a bit problematic in the practical sense because many destructive earthquakes fall below that range. In fact, 2017's deadliest earthquake, which rocked the Iran-Iraq border and took over 400 lives and injured over 7,000 was magnitude 7.3.

Crucial After Quake Hours

The team is now looking for other gravitational waves detected after other large earthquakes such as the Sumatra earthquake in 2004 and the Chile earthquake in 2011. Though some believe that there is much work to be done in order for this method to be a viable measure, other experts see it as a major contribution.

It'll be a major contribution if gravitational waves can beat down the time needed to know that a big earthquake is big," says Susan Hough, a USGS seismologist in Pasadena, California. 

Practically speaking, although gravitational waves arrive mere minutes before seismic waves, having a faster means of measuring earthquake strength could be a very important tool for public authorities to deploy the proper rescue and relief operations in the crucial hours and even minutes after the earthquake strikes. What's more, as earthquakes are sometimes followed by tsunami events, a single minute of warning could save the lives of many people in coastal areas.

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