Earthquake Prediction May Finally Be Possible; GPS Data Offers Way of Detecting Underground Tremors

According to the United States Geological Survey (USGS), there are about 500,000 detectable earthquakes in the world each year, 100 of them having the potential to cause damage. Many people may become injured, homeless, displaced, or evacuated during the emergency phase of this natural disaster.

With the technology that we currently have, it is still impossible to predict the exact time and location where an earthquake might strike. In a recent study, a group of scientists believe that Global Positioning System (GPS) data can help spot the early warning signs approximately two hours before a large earthquake strikes.

Earthquake Probability and Forecasts

Although it is not currently possible to predict exactly when and where an earthquake will likely occur, seismologists can estimate where the tremors will likely strike by calculating probabilities and forecasts.

Earthquake probabilities refer to the chances of an earthquake of a particular magnitude occurring within an area over the years. These can be calculated by getting the average rate of past seismic activity in a location. It is particularly useful in areas where earthquakes have been recorded by seismographs, which were widely used in the early 20th century.

Meanwhile, earthquake forecasts provide information on the likelihood of earthquakes over a shorter period. Forecasts are typically used in describing aftershocks, which may follow a pattern of decreasing earthquake frequency and magnitude over time.

Spotting Early Warning Signs with GPS Data

In a new seismological study, scientists Quentin Bletery and Jean-Mathieu Nocquet investigated the potential of GPS satellites in identifying a precursor for powerful earthquakes. They believe this can be determined two hours before the tremor occurs by tracking small slips in the tectonic plates as they move against each other.

Bletery and Nocquet analyzed GPS data from over 90 earthquakes with magnitudes higher than 7 in this research. The data was obtained from Nevada Geodetic Laboratory, a Reno research lab at the University of Nevada, which catalogs global GPS data.

GPS satellites can detect ground movements by measuring the position of embedded sensors and monitoring how much they have displaced over time.

The researchers tracked the shift in ground movements in 48 hours leading up to each event. They found that two hours before the quakes ruptured, there was an exponential acceleration of horizontal ground movement in a pattern consistent with "slow fault slip," an event where the ground moves without making any seismic waves or tremors.

This analysis was repeated on 100,000 random—48-hour time windows that did not occur before an earthquake to act as a control variable. Only 0.03% of the samples show a similar pattern. These findings support the idea that the "slow fault slip" pattern occurs only before earthquakes most of the time.

According to Bletery, identifying the patterns of subtle movements can help experts warn people of coming earthquakes hours in advance, but only if more advanced GPS systems are developed. Meanwhile, some experts disagree that this study's findings can help predict earthquakes moving forward.