Olivine may shake things up by changing its identity at high pressure and temperature
“It’s been a real puzzle for many scientists because earthquakes shouldn’t occur deeper than 300 kilometers,” says Ohuchi, of Ehime University in Matsuyama, Japan.made of oceanic crust — rich in olivine — plunge toward the mantle . Since the quakes’ seismic waves lose strength during their long ascent to the surface, they aren’t typically dangerous. But that doesn’t mean the quakes aren’t sometimes powerful. In 2013, a magnitude 8.
He and his team decided to put olivine itself to the test. To replicate conditions deep underground, the researchers heated and squeezed olivine crystals up to nearly 1100° Celsius and 17 gigapascals. Then the team used a mechanical press to further compress the olivine slowly and monitored the deformation.
From 11 to 17 gigapascals and about 800° to 900° C, the olivine recrystallized into thin layers containing new wadsleyite and smaller olivine grains. The researchers also found tiny faults and recorded bursts of sound waves — indicative of miniature earthquakes. Along subducting tectonic plates, many of these thin layers grow and link to form weak regions in the rock, upon which faults and earthquakes can initiate, the researchers suggest.
“The transformation really wreaks havoc with the [rock’s] mechanical stability,” says geophysicist Pamela Burnley of the University of Nevada, Las Vegas, who was not involved in the research. The findings help confirm that olivine transformations are enabling deep-focus earthquakes, she says. Next, Ohuchi’s team plans to experiment on olivine at even higher pressures to gain insights into the mineral’s deformation at greater depths.
France Dernières Nouvelles, France Actualités
Similar News:Vous pouvez également lire des articles d'actualité similaires à celui-ci que nous avons collectés auprès d'autres sources d'information.
Bryce Young’s big first half leads Alabama to win over Vanderbilt 55-3Alabama quarterback Bryce Young threw for more than 300 yards and four touchdowns in the first half, as Alabama wins their first SEC matchup of the season against Vanderbilt.
Lire la suite »
Russian police block war protests, arrest hundredsAn independent website that monitors political arrests in Russia said police detained more than 700 people on Saturday, including over 300 in Moscow.
Lire la suite »
Hubble Spies a Spectacular Spiral GalaxyThis spectacular image, by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3, reveals the stately sweeping spiral arms of the spiral galaxy NGC 5495. NGC 5495, which is located roughly 300 million light-years from Earth in the constellation Hydra, is a Seyfert galaxy, a type of galaxy with a
Lire la suite »