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

Indonesia cancels tsunami alert after strong quake

A strong magnitude 6.9 earthquake struck off Indonesia on Sunday, the US Geological Survey reported, triggering a brief tsunami warning that sent panicked residents fleeing to higher ground.

A seismologist present at the discovery of plate tectonics

As a young seismologist in the 1960s, Lynn Sykes made crucial observations of earthquakes under the ocean floors that helped solidify the theory of plate tectonics—the foundation of modern geology. Later, hoping to apply ...

Glacial sediments greased the gears of plate tectonics

Earth's outer layer is composed of giant plates that grind together, sliding past or dipping beneath one another, giving rise to earthquakes and volcanoes. These plates also separate at undersea mountain ridges, where molten ...

Study provides new insight into origin of Canadian Rockies

The Canadian Rocky Mountains were formed when the North American continent was dragged westward during the closure of an ocean basin off the west coast and collided with a microcontinent more than 100 million years ago, according ...

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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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