Related topics: quake · earth · earthquake · geologists · earth sciences

Early Earth was bombarded by series of city-sized asteroids

Scientists know that the Earth was bombarded by huge impactors in distant time, but a new analysis suggests that the number of these impacts may have been 10 times higher than previously thought. This translates into a barrage ...

'Pack ice' tectonics reveal Venus' geological secrets

A new analysis of Venus' surface shows evidence of tectonic motion in the form of crustal blocks that have jostled against each other like broken chunks of pack ice. The movement of these blocks could indicate that Venus ...

Extreme greenhouse effect heated up the young Earth

Very high atmospheric CO2 levels can explain the high temperatures on the still young Earth three to four billion years ago. At the time, our Sun shone with only 70 to 80 percent of its present intensity. Nevertheless, the ...

Geological riddle solved: 'Roof of the World' has gotten higher

There has long been controversy about whether the world's highest region, Tibet, has grown taller during the recent geological past. New results from the University of Copenhagen indicate that the 'Roof of the World' appears ...

Imaging technique could identify where landslides are likely

Each year, landslides kill thousands of people around the world and cause catastrophic property damage. But scientists are still trying to better understand the circumstances that cause them. Doing so would go a long way ...

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Plate tectonics

Plate tectonics (from the Greek τέκτων; tektōn, meaning "builder" or "mason") describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s.

The lithosphere is broken up into what are called tectonic plates. In the case of Earth, there are currently eight major and many minor plates (see list below). The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The lateral movement of the plates is typically at speeds of 50–100 mm annually.

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