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| The asthenosphere lies just below the lithosphere, which is involved in plate movements and isostatic adjustments. In spite of its heat, pressures keep it plastic, and it has a relatively low density. |
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| An earthquake (also known as a tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. |
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| In the Earth, the lithosphere includes the crust and the uppermost mantle which is joined to the crust across the mantle. The lithosphere is underlain by the asthenosphere, the weaker, hotter, and deeper part of the upper mantle. |
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A type of seismic wave, the S-wave, secondary wave, or shear wave (sometimes called an elastic S-wave) is one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves. |
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| A terrane is not necessarily an independent microplate in origin, since it may not contain the full thickness of the lithosphere. It a piece of crust which has been transported laterally, usually as part of a larger plate, and is relatively buoyant due to thickness or low density. |
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Seismic waves are waves that travel through the Earth or other elastic body, for example as the result of an earthquake, explosion, or some other process that imparts forces to the body. Seismic waves are also continually excited on Earth by the incessant pounding of ocean waves (referred to as the microseism) and the wind. Seismic waves are studied by seismologists, and measured by a seismograph, which records the output of a seismometer, or geophone. For seismic studies of oil reservoirs, hydrophones may give additional information. |
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| During an earthquake, Seismic waves propagate spherically out from the hypocenter. Seismic shadowing occurs on the opposite side of the Earth from the earthquake epicenter because the liquid outer core refracts the longitudinal or compressional (P-waves) while it absorbs the transverse or shear waves (S-waves). Outside of the seismic shadow zone both types of wave can be detected, but due to their different paths through the Earth, they arrive at different times. |
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| Mantle convection is the slow creeping motion of Earth's rocky mantle in response to perpetual gravitationally unstable variations in its density. |
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Term
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Definition
| Seismic waves are waves that travel through the Earth or other elastic body, for example as the result of an earthquake, explosion, or some other process that imparts forces to the body. |
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thin-skinned thrusting [image] |
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Definition
| Low-angle thrust faults were first recognized in 1841 by Arnold Escher von der Linth in the Alps near Glarus, Switzerland (Bailey, 1935), and by James M. Safford (1856) in Tennessee, and later by A.E. Törnebohm (1872) in Sweden and R.G. McConnell (1887) in the Canadian Rockies, but their very existence became a point of contention. |
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| A craton (Greek kratos / κρἀτος (neut.) "strength") is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. |
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| The fault surface is usually near vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are also known as sinistral faults. Those with right-lateral motion are also known as dextral faults |
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Pangaea, Pangæa or Pangea (IPA: /pænˈdʒiːə/[1], from παν, pan, meaning entire, and Γαῖα, Gaea, meaning Earth in Ancient Greek) was the supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration [2]. |
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shallow-focus earthquake [image] |
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Definition
| 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 earthquakes is less completely determined than more severe quakes |
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| A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields. Volcanic belts are found above zones of unusually high temperature |
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convection currents [image] |
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Definition
Convection in the most general terms refers to the movement of molecules within fluids[1] (i.e. liquids, gases and rheids). Convection is one of the major modes of heat transfer and mass transfer. In fluids, convective heat and mass transfer take place through both diffusion – the random Brownian motion of individual particles in the fluid – and by advection, in which matter or heat is transported by the larger-scale motion of currents in the fluid. In the context of heat and mass transfer, the term "convection" is used to refer to the sum of advective and diffusive transfer.[2] |
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Definition
The location of an earthquake's hypocenter is the position where the energy stored in the strain in the rock is released, which occurs at the focal depth below the epicentre. The focal depth can be calculated from measurements based on seismic wave phenomena. |
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| P-waves are type of elastic wave, also called seismic waves, that can travel through gasses (such as sounds), elastic solids and liquids, including the Earth. |
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Definition
| As a crustal plate moves further from an oceanic ridge, it cools and becomes increasingly dense. This causes it to sink beneath the continental crust in a subduction zone. The weight of this sinking, cooling plate causes a major pulling action, which causes the rest of the plate to be pulled downwards as well. |
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| A volcanic arc is a chain of volcanic islands or mountains formed by plate tectonics as an oceanic tectonic plate subducts under another tectonic plate and produces magma. |
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deep-focus earthquake [image] |
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Definition
| deep-focus earthquake is an earthquake that occurs at depths between 300 and 700 km beneath the Earth's surface.[1] Their cause is still not entirely understood since subducted lithosphere at that pressure and temperature regime should not exhibit brittle behavior. |
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| In geology, a hotspot is a location on the Earth's surface that has experienced active volcanism for a long period of time. |
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Ridge-push is a proposed mechanism for plate motion in plate tectonics. Because mid-ocean ridges lie at a higher elevation than the rest of the ocean floor, gravity causes the ridge to push on the lithosphere that lies farther from the ridge. |
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Term
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Definition
| In seismology, several types of surface waves are encountered. Surface waves, in this mechanical sense, are commonly known as either Love waves (L waves) or Rayleigh waves,a seismic wave is a wave that travels through the Earth, often as the result of an earthquake or explosion. |
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Term
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Definition
| A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. |
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