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According to new research, the vast majority of earthquakes we feel happen soon after, according to new research that offers new insights into how seismology works.
The discovery offers an unprecedented overview of
what happens before moderate and important earthquakes – and scientists are
finding that the vast majority of them occur after smaller earthquakes begin to undulate below the ground, sometimes days or even weeks before the main shock.
"One of the biggest questions in seismic seismology is how to start earthquakes," said lead author Daniel Trugman, a seismologist at Los Alamos National Laboratory. "We find that most, if not all, [significant] Earthquakes are preceded by forces that we can detect "with a new computer technique.
Previously, scientists have observed that only half of moderate earthquakes had smaller precursor events. Now, this new study on earthquakes in southern California of at least magnitude 4 between 2008 and 2017 reveals that at least 72% of them had earlier earthquakes earlier.
"The board activity is high is ubiquitous in Southern California," the study concluded.
"It's surprising," said co-author of the study, Zachary Ross, an assistant professor of geophysics at Caltech. "It's important to understand the physics of earthquakes. Are they silent until this great event? Or is there a process of weakening the fault, or evidence that the fault changes before this more important event? "
The study shows how the answer is probably the last explanation.
This discovery now allows scientists to better understand how most earthquakes are generated. Understand that even moderate tremors probably occur after a series
The idea of small children gives even more weight to the idea that seismic sequences can grow, which is reminiscent of the growing epidemic of the disease. In fact, the study shows that the sequences of the anterior drumstick range from 3 days to 35 days before the main shock.
The discovery does not mean that we should all be suddenly worried about small earthquakes. Statistically speaking, only 5% of earthquakes are followed by a disaster.
Nor does it mean that researchers are closer to predicting the exact times and locations of major earthquakes, which is widely considered impossible.
"The vast majority of earthquakes, even if abnormal activity is triggered, subsides most of the time, most of the time," Ross said.
But understanding how earthquakes grow can only help scientists improve replica forecasts. This would help the public to understand when there is a greater risk, such as when the risk of a major earthquake changes from a base risk of 1 in 10,000 to 1 in 1,000 based on a previous earthquake.
"We are definitely moving towards statistical forecasts," said Trugman.
The discovery could also help improve the speed of earthquake early warning systems, Ross said. If the computer has detected micro-tremors near a major failure and knows that most major earthquakes are preceded by smaller earthquakes, this can help the system make a faster decision by issuing a warning as soon as an earthquake began to break along a fault.
The discovery of the study, published in the journal Geophysical Research Letters several weeks ago, was only made possible by the discovery of a new technique for detecting very small earthquakes – earthquakes of magnitude 0 and 1, and sometimes negative. 2
But detecting these micro-tremors is hard to do. Currently, this can not be done in real time and this can only be done by introducing into a supercomputer past earthquakes, which takes a few weeks.
Having a more accurate view of earthquakes in southern California suddenly allowed scientists to detect many previously unseen thermal shocks.
"This new information comes from events of the smallest magnitude that were previously invisible," Ross said.
For the new study, Trugman and Ross decided to focus on 46 of the largest earthquakes in southern California between 2008 and 2017 (excluding those that were replicas of other more important events). They found that 33 out of 46 earthquakes showed a statistically significant increase in the number of fangs compared to the normal rate of earthquakes in this region.
They discovered a particularly long sequence before the magnitude 5.1 La Habra earthquake of March 2014. There were earthquakes of magnitude 0 and 1 as early as 17 days before the main shock.
The magnitude 7.2 earthquake of Easter Sunday 2010, widely felt in Southern California, has not been included in the analysis, as its epicenter is located in Baja California. But this earthquake was preceded by a remarkable sequence of the stomach.
Scientists were unable to determine a specific pattern for crampons that would lead to an earthquake of magnitude 4 or higher. Sometimes it looked like a burst of earthquakes near what would become the epicenter of the main shock a few days or hours later. Other times, it would be a general increase in the earthquake rate in the region in general before the main shock.
They also found that shallower main shocks tended to have more crampons, as did areas with higher heat flux, such as areas around the Coso Volcanic Field and the Salton Sea.
are warmed by the magma.
The results help solve a long mysterious earthquake that scientists could not explain before. In laboratory experiments where scientists simulated earthquakes with sensitive equipment, there would always be small earthquakes before the main earthquake. "It's never silent until the final failure," said Ross about the laboratory earthquakes.
The results suggest that it is possible for all moderate and important earthquakes to be preceded by something smaller, but to reach this conclusion, more studies are needed.
"It's hard to imagine this huge fault that stays completely silent until just one point starts to fail," Ross said.
"Physically, it seems a bit hard to imagine."
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