Core

The USGS supports an important National Earthquake Hazards Program. As a small part of that effort there have been studies attempting to correlate magnetic variations, or more precisely, electro-magnetic variations, with earthquakes. Electro-magnetic...
Learn what the USGS is doing to understand natural hazards and mitigate their effects on human life and property at the USGS Natural Hazards Web site, which has information on the following related hazards topics:  ...
Yes. We know this from an examination of the geological record. When lavas deposited on the Earth's surface subsequently solidify, and when sediments deposited on ocean and lake bottoms solidify, they often preserve a signature of the ambient magnetic...
One of the most important jobs that a scientist has is to identify -- from among all the possible causes and effects in nature -- those that are the most important and strictly and necessarily causally related, and those that are simply insignificant and...
The magnetic field of the Earth does protect us from fast-moving charged particles streaming from the Sun, and so does the atmosphere. It is not clear whether or not the radiation that would make it to the Earth's surface during a polarity transition,...
Yes. There is evidence that some animals, probably most notably sea turtles, have the ability to sense the Earth's magnetic field (although probably not consciously) and to use this sense along with their several other senses for purposes of navigation....
The needle of a compass is a small magnet that is allowed to pivot in the horizontal plane. The needle experiences a torque from the ambient magnetic field of the Earth. The reaction to this torque is the needle's preferred alignment with the horizontal...
In a sense, yes. You probably know that the Earth is stratified. In radius it is composed of layers having different chemical composition and different physical properties. The crust of the Earth has some permanent magnetization, and the core of the...
Fields fill the space between matter and they determine how it is that bits of matter can exert forces on other bits of matter at a distance.  There are several different fields in nature, and their reality is demonstrated by our observation of the...
Briefly, as the result of radioactive heating and chemical differentiation, the Earth's outer core is in a state of turbulent convection. This sets up a process that is a bit like a naturally occurring electrical generator, where the convective kinetic...