2023-07-22 04:10:34
Scientists may have taken an important step towards earthquake prediction. Image: Cigdem Simsek/Picture allianc
A couple of seismologists from the University of the French Riviera have discovered what could be an accurate way to predict earthquakes.
Trying to predict the arrival of a major earthquake is a challenge yet to be met, although a new study provides evidence that there is a precursor slip phase of the fault that occurs two hours before the seismic rupture.
The research signed by French scientists and published Science analyzes Global Positioning System (GPS) time series data from nearly 100 major earthquakes around the world.
earthquake prediction
Near-term earthquake prediction and the ability to alert minutes to months before an earthquake occurs depends on a definitive and observable precursor geophysical signal.
Previous retrospective studies of several large earthquakes have suggested that a precursor phase of slow seismic slip may be observed on the faults before a mainshock.
However, the relationship between these observations and seismic ruptures is not well understood, since they do not directly precede an event and frequently occur without being followed by an earthquake, so the existence of a clear precursor signal capable of predicting large earthquakes remains uncertain.
Short-term precursor slide
The new study presents a systematic global search for the short-term precursor slip of faults before large earthquakes occur. Using high-speed GPS time-series data from 3,026 geodetic stations around the world, fault displacement was measured up to two hours before 90 earthquakes of magnitude 7 or greater occurred.
Statistical analysis of the data revealed “a subtle signal consistent with a period of exponential acceleration of the fault slip near the hypocenter of the eventual earthquake, which began approximately two hours before the rupture,” the publication explains.
These findings suggest that many large earthquakes begin with a preslide phase or that the observations represent the end of a much longer and more difficult-to-measure preslide process, the authors say.
Seismic monitoring instrumentation lacks coverage
Although the study provides evidence of a precursor signal, the team says that currently deployed seismic monitoring instrumentation lacks the coverage and precision needed to identify or monitor precursor slip at the scale of individual earthquakes.
An article accompanying the research indicates that while the results “suggest there may be an hours-long precursor phase, it is unclear whether these slow-slip accelerations are clearly associated with large earthquakes or could ever be measured in events.” with the precision necessary to provide a useful warning.
The paper’s author, Roland Bürgmann of the University of California at Berkeley (USA) and who was not involved in the research, adds that if it is confirmed that the nucleation (pre-tremor phase) of earthquakes usually implies a precursor phase hours long and the means to measure it reliably are developed, a precursor alert could be issued.”
FEW (EFE, Science)
#Seismic #alert #GPS #data #predict #earthquakes