asthenosphere

[ as-then-uh-sfeer ]

noun

, Geology.

1. the region below the lithosphere, variously estimated as being from fifty to several hundred miles (eighty-five to several hundred kilometers) thick, in which the rock is less rigid than that above and below but rigid enough to transmit transverse seismic waves.

asthenosphere

/ əsˈθiːnəˌsfɪə; -ˈθɛn- /

noun

1. a thin semifluid layer of the earth (100–200 km thick), below the outer rigid lithosphere, forming part of the mantle and thought to be able to flow vertically and horizontally, enabling sections of lithosphere to subside, rise, and undergo lateral movement See also isostasy

asthenosphere

/ ăs-thĕn′ə-sfîr′ /

1. The upper part of the Earth's mantle, extending from a depth of about 75 km (46.5 mi) to about 200 km (124 mi). The asthenosphere lies beneath the lithosphere and consists of partially molten rock. Seismic waves passing through this layer are significantly slowed. Isostatic adjustments (the depression or uplift of continents by buoyancy) take place in the asthenosphere, and magma is believed to be generated there.
2. Compare atmosphere

Word History and Origins

Origin of asthenosphere¹

First recorded in 1910–15; from Greek asthen(ḗs) “frail, weak, sickly” + -o- + -sphere; asthenia

Word History and Origins

Origin of asthenosphere¹

C20: from astheno-, from Greek asthenēs weak + sphere

Example Sentences

Understanding the origin of this seismic wave velocity drop and attenuation at the oceanic LAB is crucial for deciphering the asthenosphere's low viscosity and how it facilitates the movement of tectonic plates over the Earth's surface, giving rise to mountain-building processes, earthquakes, and volcanism.

From Science Daily

In this regard, a team of researchers from Japan, led by Professor Takashi Yoshino from the Institute for Planetary Materials at Okayama University, has recently investigated the effect of water on the seismic properties of titanium-free olivine rocks, similar to those found in the asthenosphere.

From Science Daily

"We experimentally determined the seismic wave attenuation characteristics, parameters for ascertaining the softness of the lithosphere and asthenosphere, under high temperature and pressure using our short-period oscillation generation technology," explains Prof. Yoshino.

From Science Daily

These observations suggest that the oceanic asthenosphere must contain water.

From Science Daily

This layer appears to glide over a weaker region below called the asthenosphere, characterized by high seismic attenuation and low shear wave velocity.

From Science Daily