14 DAY TRIAL // Some really wacky things happen deep in our planet's guts on a regular basis, and, were it not for scientists, we, mere mortals, would forever be in the dark about these fits that Earth likes to throw just to pass the time.
Not to beat about the bush, a recent paper in the journal Science tells the tale of how, using data provided by seismometers, researchers were able to document a deep earthquake that ruptured at impressive speed.
The investigation was carried out by researchers with the Scripps Institution of Oceanography at the University of California, San Diego, in the United States, and the shake it focused on occurred on May 24, 2013.
In their paper in the journal Science, the scientists detail that the earthquake in question had a magnitude of 6.7, and that it struck under the Sea of Okhotsk, offshore Russia's Kamchatka Peninsula, Phys Org informs.
What sparked the researchers' interest in this shake was the fact that, despite its magnitude, the earthquake did not last very long. On the contrary, data obtained by seismometers indicated that the event was over in the blink of an eye.
“For a 6.7 earthquake you would expect a duration of seven to eight seconds, but this one lasted just two seconds,” Geophysics Professor Peter Shearer with the Scripps Institution of Oceanography explains in a statement.
Together with fellow researchers, Peter Shearer argues that, according to information at hand, this shake, which was an aftershock of an 8.3 magnitude earthquake that occurred on the very same day, lasted only 2 seconds due to its rupture velocity.
Thus, the earthquake, estimated to have occurred at a depth of about 640 kilometers (approximately 400 miles), is said to have ruptured at a speed of 8 kilometers per second (roughly 5 miles per second), Peter Shearer and colleagues explain.
Otherwise put, the earthquake was the result of two sides of a fault ripping apart at such impressive speed that the rupture itself traveled about as fast as the resulting waves of seismic energy. Scientists claim that such phenomena are best described as seismic sonic booms.
Its rupturing speed means that, when compared to the majority of earthquakes that have until now been documented at the aforementioned depth, this aftershock that struck on May 24, 2013, under the Sea of Okhotsk had rupture velocity about 50% greater.
“This is the first definitive example of supershear rupture for a deep earthquake since previously supershear ruptures have been documented only for shallow earthquakes,” Peter Shearer wishes to stress.
“One quarter of earthquakes occur at large depths, and some of these can be pretty big, but we still don't understand why they happen. So this earthquake provides a new observation for deep earthquakes and high-rupture speeds,” scientist Zhongwen Zhan comments on the importance of this discovery.