The asthenosphere is a layer of the Earth's interior that includes part of the lower crust and part of the mantle. The upper boundary of the asthenosphere is roughly 50 miles below the ground's surface. Its lower boundary, however, is inconsistent and depends primarily on temperature. Experts at the United States Geological Survey estimate its average thickness as 112 miles.
Asthenosphere comes from the Greek word "asthenos," which means "weak." This is a reference to the asthenosphere's fluidity and mechanical weakness. According to geologists at San Diego State University, the upper portion of the asthenosphere is semi-solid, but in many places its lower regions are molten. The asthenosphere is composed of iron-magnesium silicates and has an overall consistency akin to hot tar. Molten rock in the Earth's deeper layers is much hotter and behaves as a true liquid.
The region directly above the asthenosphere is the lithosphere, the entirely solid uppermost region of the Earth's crust. Earthquakes that occur in the lithosphere are potentially catastrophic because of the severe jarring forces created when two tectonic plates interact. Because the asthenosphere is more malleable, the deep-zone earthquakes that occur in it often go undetected. The United States Geological Survey reveals earthquakes also occasionally occur even deeper in the layers below the asthenosphere.Learn More
The distance between the Earth's crust to the Earth's core is approximately 3,958 miles. Of this distance, the crust only makes up approximately 21 miles. Between the crust and the outer core is the mantle, which spans a distance of 1,774 miles.Full Answer >
The Earth's mantle is 2,900 kilometers (1,802 miles) thick. The mantle lies between the core and the outer crust layer and consists of four layers: lithosphere, asthenosphere, upper mantle and lower mantle.Full Answer >
The immense pressure from the other parts of the planet keep the extremely hot iron of the Earth's inner core from melting. The iron in the inner core maintains a temperature of around 9,000 to 13,000 degrees Fahrenheit.Full Answer >
The temperature of Earth's inner core is estimated to be between 9,000 to 13,000 degrees Fahrenheit, as stated by National Geographic. The planet's innermost region is primarily made up of a solid iron composition due to extreme levels of pressure.Full Answer >