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- Dictionaryearthquake/ˈəːθkweɪk/
noun
- 1. a sudden violent shaking of the ground, typically causing great destruction, as a result of movements within the earth's crust or volcanic action.
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Sep 12, 2024 · Earthquake, any sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks. Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another.
Sep 12, 2024 · Earthquake magnitude is a measure of the “size,” or amplitude, of the seismic waves generated by an earthquake source and recorded by seismographs. (The types and nature of these waves are described in the section Seismic waves .)
Sep 12, 2024 · Furthermore, earthquake intensity, or strength, is distinct from earthquake magnitude, which is a measure of the amplitude, or size, of seismic waves as specified by a seismograph reading. See below Earthquake magnitude.
Sep 17, 2024 · Seismic wave, vibration generated by an earthquake, explosion, or similar energetic source and propagated within the Earth or along its surface. Earthquakes generate four principal types of elastic waves; two, known as body waves, travel within the Earth, whereas the other two, called surface
Aug 14, 2024 · Anderson-Wood torsion pendulum seismograph Schematic diagram of a 1924 Anderson-Wood torsion pendulum seismograph, the type used by seismologist Charles F. Richter to define his earthquake magnitude scale. A small copper cylinder (C) was attached to a tungsten wire (T) between the poles (N, S) of a U-shaped permanent magnet. In ...
epicentre, point on the surface of the Earth that is directly above the underground point (called the focus) where fault rupture commences, producing an earthquake. The effects of the earthquake may not be most severe in the vicinity of the epicentre.
Sep 12, 2024 · Earthquake - Seismic Waves, Properties, Geology: At all distances from the focus, mechanical properties of the rocks, such as incompressibility, rigidity, and density, play a role in the speed with which the waves travel and the shape and duration of the wave trains. The layering of the rocks and the physical properties of surface ...
Sep 12, 2024 · Earthquake - Tectonics, Seismology, Faults: Tectonic earthquakes are explained by the so-called elastic rebound theory, formulated by the American geologist Harry Fielding Reid after the San Andreas Fault ruptured in 1906, generating the great San Francisco earthquake. According to the theory, a tectonic earthquake occurs when ...
Sep 12, 2024 · Earthquake - Volcanism, Seismology, Tectonics: A separate type of earthquake is associated with volcanic activity and is called a volcanic earthquake. Yet it is likely that even in such cases the disturbance is the result of a sudden slip of rock masses adjacent to the volcano and the consequent release of elastic strain energy. The ...
Sep 12, 2024 · Earthquake - Shallow, Intermediate, Deep Foci: Most parts of the world experience at least occasional shallow earthquakes—those that originate within 60 km (40 miles) of the Earth’s outer surface. In fact, the great majority of earthquake foci are shallow. It should be noted, however, that the geographic distribution of smaller ...
