early Monday morning, A magnitude 7.8 earthquake hit Turkey and Syria, followed nine hours later by a magnitude 7.5 aftershock. The death toll has now passed 3,800, and rescuers have just begun combing through the collapsed buildings.
Aftershocks continue to shake the region as local faults adapt to such a massive initial tremor, and scientists say this process could last not just days, but months and even years. There is even a small possibility of aftershocks greater than From the original earthquake.
“The risk of aftershocks is inherently greatest immediately after the mainshock, but this quake is followed by significant aftershocks for years,” said David Oglesby, a geophysicist at the University of California, Riverside. Let’s go,” he said. “Right now, we can predict more aftershocks of magnitude 5, maybe 6 or so in the region. .”
It would make the humanitarian crisis in Turkey and Syria even worse. “We can’t tell people: All right, all right, we’re done. It was terrible and it’s over now. Because that’s not how the Earth works,” says seismic geologist Wendy Bohon. “After such a traumatic and devastating experience, it is truly disappointing to know that these people will have to continue to feel the shaking of the earthquake for a long time.”
Earthquakes are products of plate tectonics. Plates are giant boulders that move independently in the crust, but touch each other along faults. “Eventually, stress and strain will overcome the friction that holds rocks together, and they will break in an earthquake,” Bohon says. “When a rock breaks, it releases energy in the form of waves. Those waves are what we feel as tremors.”
Monday morning’s main quake occurred along about 125 miles along the East Anatolian Fault, a well-known fault line in southern Turkey. Specifically, this was a strike-slip earthquake. This means that stress built up between two blocks moving horizontally in opposite directions until the fault ruptured. Also, the ground was very shallow, which caused more violent shaking at the surface. (The San Andreas Fault in California is also a strike-slip fault that destroyed much of San Francisco in 1906.)
In general, the larger the main shock, the larger the aftershocks, and the frequency and magnitude tend to decrease with the passage of time. As can be seen in this map, not only are aftershocks of varying intensities clustered along the fault line of the original earthquake, but a separate, but connected, northern quake appears to have produced an aftershock of magnitude 7.5. They also cluster on fault lines. “It’s a very complex system of faults because the crust is really squashing,” said Alice Gabriel, a seismologist at the Scripps Institution of Oceanography.
That complexity means that what happens at one failure doesn’t stop there. The stress that led to the magnitude 7.5 quake may have been accumulating for some time, and the shock of the main quake released it. So in the end we probably had a big earthquake a little earlier.” Such aftershocks are “just other quakes and nothing distinguishes them. Very large quakes change the stresses in the earth’s crust so much that they locally overwhelm the rate of occurrence of all other quakes.” Just increase it.”
