Earthquakes: Study examines what causes catastrophic events
Scientists have made further progress toward identifying the key circumstances of devastating earthquakes, researchers say.
What distinguishes areas prone to mild earthquakes from areas likely to experience large earthquakes in the future may come down to the principle of friction, according to new research published last week. I have. Peer-reviewed journal Science.
Friction describes the resistance force when two materials slide over each other. Certain friction phenomena that determine how quickly faults recover after earthquakes could also be key to determining whether faults are at risk of larger earthquakes in the future, researchers say. .
In essence, fast-recovering faults after an earthquake can produce a stiffer basement that is likely to split dramatically at some point in the future, while slower-recovering faults are more likely to split along the fault. It allows for more continuous and harmless movement.
This allows researchers to start focusing on danger zones.
“The same physics and logic should apply to all different kinds of faults around the world,” said co-lead author of the study, director of the University of Texas Geophysical Laboratory at the Jackson Graduate School of Geosciences. Damien Saffer is said in a press release. “With appropriate samples and field observations, we can begin to make testable predictions about how large and how often seismic slip events will occur on other major faults, such as Cascadia in the Pacific Northwest. became.”
Earthquakes occur because the Earth’s crust is not one solid, immovable part. Instead, it consists of numerous tectonic plates that move very slowly as the Earth’s molten core continues to move.
Geological faults are fissures in the crust and the rock layers above it. There are faults where each tectonic plate touches another, but there are also faults that do not exactly coincide with plate boundaries. The Earth is made up of many layers of rock that move slowly over each other, occasionally creating a frictional environment suitable for earthquakes.
During an earthquake, the regular movements that are imperceptible in everyday life are disturbed by sudden movements along faults. This movement also sends out shock waves that can be felt by everyone within the radius of the earthquake itself.
Earthquakes vary widely in size and strength, with the worst quakes capable of collapsing buildings, tearing cities apart, and instantly claiming thousands of lives.
Nearly 45,000 people have died so far in the 7.8-magnitude earthquake that hit Turkiye and Syria in early February, according to recent figures. More buildings were reported to have collapsed in Turkiye’s Hatay province on Monday as another magnitude-6.4 earthquake hit the region.
The devastating potential of earthquakes underscores how important it is to try to unravel the mechanisms behind large earthquakes.
In pursuit of that goal, researchers created tests for this new study that examined rocks from a famous fault off the coast of New Zealand.
This particular fault is often prone to “slow-motion” earthquakes and is composed of clay-rich rocks.
The researchers took rocks extracted from about half a mile below the seafloor, squeezed them in a hydraulic press, and investigated how quickly they could recover from this pressure and whether they slipped on each other or exhibited higher pressures. bottom. amount of friction. They found that the rocks healed slowly and moved easily against each other.
Incorporating this data into a computer model predicted that this type of rock would be associated with small slow-motion earthquakes that occur about every two years. This agrees almost exactly with real data from this fault in New Zealand.
This suggests that these clay-rich rocks, present at many earthquake sites around the world, actually help slow and calm earthquakes by promoting the slow movement of the plates together. Researchers believe it shows By allowing rocks to move back very quickly and resist movement for long periods of time, instead of allowing more movement within the plate, the resulting earthquakes are smaller and more frequent.
It’s the same friction phenomenon that makes it take more effort to move a stationary box in the first place than to keep it moving, researchers say.
Does this mean we have the key to predicting when and where the next big earthquake will occur?
Not yet, according to researchers. There is still a lot of work to be done before earthquake prediction becomes that simple. However, the study could indicate which faults are likely to have giant tremors.
“This doesn’t really come close to predicting an earthquake, but it’s a question of whether the fault could slip quietly without an earthquake, or whether it’s a big deal,” said Srisharan Shreedharan, an associate professor at Utah State University. It tells us how large, ground-shaking earthquakes are likely to occur.” The co-chair of the study said in a release.
We already know that some large faults do not have a history of small tremors that this study believes are signs of slowly healing and safer rock structures.
For example, the Cascadia Fault, a tectonic plate boundary that stretches down the coast of North America from Vancouver Island to northern California in the United States, has no such history.
The Pacific Northwest Seismic Network hopes to place sensors in key regions of this fault to investigate whether they mask the potential for catastrophic future earthquakes. Director Harold Tobin, who was not involved in the new study, said the study’s results give them a clear reason to continue.
“We want to focus on processes in the shallow part of the fault, as that governs the magnitude of the tsunami,” Tobin said in a release. “Fault repair doesn’t explain everything, but it does give us a window into the workings of subduction zone faults that didn’t exist before.”