A groundbreaking analysis of GPS time-series data has unveiled the potential for detecting a precursory phase of fault slip occurring approximately two hours before large earthquakes. The research on nearly 100 significant seismic events worldwide provides hope for short-term earthquake prediction. However, current monitoring tools need help detecting such slips at the individual earthquake scale, raising questions about practical earthquake prediction.
GPS Data Reveals Precursory Fault Slip
Through a systematic global analysis of GPS time-series data from 3,026 geodetic stations worldwide, researchers Quentin Bletery and Jean-Mathieu Nocquet discovered evidence of a precursory phase of fault slip preceding 90 earthquakes of 7 or higher. The findings indicate that a subtle signal of exponential acceleration of fault slip appears near the earthquake’s hypocenter, emerging approximately two hours before the seismic rupture.
The Quest for Short-term Earthquake Prediction
The ability to predict large earthquakes within minutes to months before their occurrence remains a long-standing goal in seismology. Short-term earthquake prediction relies on identifying observable geophysical precursor signals. Previous studies have suggested the existence of slow aseismic slip in faults before main shocks. Still, the direct connection to seismic ruptures has remained unclear.
Significance and Challenges
The research by Bletery and Nocquet indicates that many large earthquakes may initiate with a precursory phase of slip. However, it is still being determined if the observed slow-slip accelerations are uniquely associated with large earthquakes or part of a more complex, challenging-to-measure process of precursory slip. Furthermore, the current earthquake monitoring instruments need more coverage and precision to detect or monitor precursory decline on an individual earthquake basis.
The discovery of a potential precursory phase of fault slip through GPS data analysis brings hope for the future of short-term earthquake prediction. While the findings open avenues for further research and development of precursor warning systems, the current limitations in monitoring tools call for continued efforts to refine the accuracy and coverage necessary for practical application in earthquake prediction.
Reference: “The precursory phase of large earthquakes” by Quentin Bletery and Jean-Mathieu Nocquet, 20 July 2023, Science.