Scientists have long assumed the Earth小蝌蚪APP檚 mantle, which makes up the bulk of the planet小蝌蚪APP檚 volume, wasn小蝌蚪APP檛 magnetic.
A 小蝌蚪APP geoscientist and an international team of scholars have concluded that previous researchers were wrong.
Findings by UL Lafayette小蝌蚪APP檚 Dr. Eric C. Ferr茅 and his collaborators counter the decades-long belief that the Earth小蝌蚪APP檚 magnetism derived only from minerals within the crust and core, two of the planet小蝌蚪APP檚 three layers. The third and largest layer, the mantle, which comprises about 84 percent of the Earth小蝌蚪APP檚 volume, was thought too hot to retain its magnetism.
Not so, Ferr茅 and his collaborators , an online peer-reviewed journal.
Parts of the upper mantle, located between 30 and 670 kilometers (18 and 416 miles) below the Earth小蝌蚪APP檚 surface, contain magnetite and a previously unknown type of iron oxide, both of which retain magnetic properties. That小蝌蚪APP檚 despite temperatures up to 700 degrees Celsius (1,292 degrees Fahrenheit).
That means minerals within the upper part of the mantle are playing a previously unknown role in producing the Earth小蝌蚪APP檚 magnetic field, without which 小蝌蚪APP渨e would be toast,小蝌蚪APP said Ferr茅, director of the in the .
小蝌蚪APP淭he magnetic field is precious to us. Without the magnetic field generated inside the Earth, most living species would be 'fried' by cosmic radiations. The main reason why there is life on Earth is because we are sheltered by this magnetic field.小蝌蚪APP
The mantle has an additional importance, Ferr茅 explained. It小蝌蚪APP檚 where earthquakes are born.
小蝌蚪APP淯p until recently, we did not really have much knowledge about the magnetic aspect of this earthquake machine. We saw it through the prism of seismic data and gravity to some extent. But now we have a new tool that allows us to see things with a completely different viewpoint.小蝌蚪APP
Ferr茅 said the behavior of rocks inside the Earth小蝌蚪APP檚 mantle determines where, when and whether an earthquake will occur. Now, scientists must consider what role magnetism plays in those dynamics. Doing so may help pinpoint where future tremors will occur and could add layers of understanding to past seismic events as well, he added.
In addition to Ferr茅, the study小蝌蚪APP檚 authors are Ilya Kupenko and Carmen Sanchez-Valle, 小蝌蚪APP of M眉nster, Germany; F谩tima Mart铆n-Hern谩ndez, Complutense 小蝌蚪APP of Madrid, Spain; and Dhananjay Ravat, 小蝌蚪APP of Kentucky, Lexington.
The interdisciplinary, global team used data from satellites that track changes inside the Earth小蝌蚪APP檚 interior to reach its conclusions. In addition, researchers replicated conditions deep inside the Earth in a laboratory using a machine Ferr茅 compared to a pressure cooker.
小蝌蚪APP淭hey take a very tiny piece of rock and they put it inside the vessel that essentially reproduces the high-pressure conditions that exist inside the Earth. And when they did that, they were able to see that in a simulation of the Earth小蝌蚪APP檚 interior conditions, there were magnetic minerals that we didn't know about before.小蝌蚪APP
These research methods are necessary, he explained, to understand what小蝌蚪APP檚 happening in areas within the Earth小蝌蚪APP檚 interior that are impossible to reach.
小蝌蚪APP淲hen you go to the doctor, the doctor examines you and, at times, they prescribe different types of exams and scans. You can take blood samples and urine samples. You can take an X-ray of your chest. You can take an MRI. All of these different medical techniques inform you about what小蝌蚪APP檚 going on inside of the body of the patient.小蝌蚪APP
Ferr茅 continued: 小蝌蚪APP淥ur planet essentially works the same way, but if you want to know what is inside the planet, you cannot really go inside. You can go inside a deep mine, maybe three kilometers below the surface, but you need to have techniques and methods that are going to allow you to probe inside the Earth.
小蝌蚪APP淭he deeper you go, the better you are going to understand what is going on at the surface.小蝌蚪APP
Photo caption: Dr. Eric C. Ferr茅 is director of UL Lafayette小蝌蚪APP檚 School of Geosciences in the Ray P. Authement College of Sciences. (Photo credit: Doug Dugas / 小蝌蚪APP)