Chile earthquake shows earth more active in past 15 years: Scientist
The 8.8-magnitude earthquake that shook Chile on Saturday was not outside the realm of normal, but the Earth has been more active over the past 15 years or so relative to a time period in the past, according to a scientist.
"Relative to the 20-year period from the mid 1970's to the mid 1990's, the Earth has been more active over the past 15 or so years," Fox News quoted Stephen S. Gao, a geophysicist at Missouri University of Science and Technology, as saying.
"We still do not know the reason for this yet. Could simply be the natural temporal variation of the stress field in the earth's lithosphere," he added.
The Chilean earthquake, and the tsunami it spawned, originated on a hot spot known as a subduction zone, where one plate of Earth's crust dives under another.
It's part of the very active "Ring of Fire," a zone of major crustal plate clashes that surround the Pacific Ocean.
"This particular subduction zone has produced very damaging earthquakes throughout its history," Randy Baldwin, a geophysicist with the U.S. Geological Survey (USGS), said.
The world's largest quake ever recorded, magnitude 9.5, occurred along the same fault zone in May 1960.
Even so, magnitude-8 earthquakes occur globally, on average, just once a year.
Since magnitudes are given on a logarithmic scale, an 8.8-magnitude is much more intense than a magnitude 8, and so this event would be even rarer, said J. Ramsn Arrowsmith, a geologist at Arizona State University.
The Ryukyu Islands of Japan were hit with a 7.0-magnitude quake just last night.
The Japanese quake, the Haiti quake and now Chile make it seem Earth is becoming ever more active.
But in the grand scheme of things, geologists say this is just Mother Nature as usual.
"From our human perspective with our relatively short and incomplete memories and better and better communications around the world, we hear about more earthquakes and it seems like they are more frequent," Arrowsmith said.