California may experience a major earthquake with a magnitude of 6 in the coming months. This would be one of the biggest seismic events in the last 20 years.
Recurrent Earthquakes
According to the "Seismic attenuation and stress on the San Andreas Fault at Parkfield: are we critical yet?" study, quakes occur every 22 years in the San Andreas Fault's Parkfield section in central California. This section stretches across Eureka and ends slightly past Palm Springs.
Along this fault stretch, the most recent earthquake was in 2004, a magnitude-6 earthquake that hit the area. It was preceded by a 1983 quake with a 6.7 magnitude. In 1966, a quake with a 6.0 magnitude occured; and in 1934, it was a 6.5 magnitude quake.
According to Luca Malagnini, the study's lead researcher, Parkfield could be close to the end of its silence. This year, an earthquake could hit the fault line once more.
San Andreas Fault Line Could See Major Earthquake This Year
For a long time, scientists have monitored the San Andreas Fault Line as a possible source of the massive "Big One" earthquake.
Experts think that a major earthquake, typically measured as a quake with a magnitude of at least 7.0, may kill over 1,800 individuals, injure roughly 50,000, and cause over $200 billion worth of damage.
Malagnini, who is also the director of research at the National Institute of Geophysics and Volcanology, thinks that the Parkfield section of the fault could experience a quake this year. However, the earthquake may not hit the epicenter of the 2004 event.
Though the window of the earthquake is nearing, scientists say that the area has not been exhibiting heightened seismic activity.
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Earthquake Indicator
The researchers went to uncover a potential pattern of the quakes in Parkfield. They look into fault line measurements that led up to six weeks before each earthquake. They found a different signal indicating rock cracks opening and closing within the strain area.
With nearly 23 years' worth of seismic measurements from the region, they determined that a specific preparatory phase, which involves the opening and closing of racks beneath the surface of the Earth, could signal an impending earthquake.
As this takes place, sound waves move through the ground differently. Such measurements are known as seismic wave attenuation, which describes the movement of sound waves through rocks. In a process known as attenuation, waves naturally lose their energy as they move through rocks.
Earthquakes are waves of high energy. However, at a fault line, small waves could occur even without an earthquake. Scientists investigated this type of wave.
The scientists discovered that certain wave types lost energy quickly in the six weeks before the 2004 earthquake. Others, on the other hand, gradually lost their power.
Waves of high frequency lost their energy more slowly, while low-frequency ones lost energy more quickly as the quake neared.
The researchers note that the fact that there are not many volcanoes present in the area could aid the matter. Since no volcanoes are nearby, the researchers can be more confident that the waves they gauge are from the tension that builds in the fault.
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