מילון מונחים

USGS, Earthquake Hazards Program Glossary, "Earthquake": "A term used to describe both sudden slip on a fault AND the ground shaking that occurs from the radiated seismic energy during the slipping event."

USGS, Glossary, "Hypocenter/focus": "The point within the earth where an earthquake rupture starts."

USGS, Glossary, "Epicenter": "The point on the earth's surface vertically above the hypocenter (or focus)".

USGS, Glossary, "Focal depth": "The depth of an earthquake hypocenter."

USGS, Glossary, "Mainshock": "The largest earthquake in a sequence, sometimes preceded by one or more foreshocks, and almost always followed by many aftershocks."

USGS, Glossary, "Foreshocks": "Relatively smaller earthquakes that precede the largest earthquake in a series, which is termed the mainshock. Not all mainshocks have foreshocks."

USGS, Glossary, "Aftershocks": "Aftershocks can continue over a period of weeks, months, or years. In general, the larger the mainshock, the larger and more numerous the aftershocks, and the longer they will continue."

USGS, Glossary, "Seismicity": "The geographic and historical distribution of earthquakes."

USGS, Glossary, "Magnitude": "A number that characterizes the relative size of an earthquake. Magnitude is based on measurement of the maximum motion recorded by a seismograph. [...] The moment magnitude (Mw) scale, based on the concept of seismic moment, is uniformly applicable to all sizes of earthquakes but is more difficult to compute than the other types. All magnitude scales should yield approximately the same value for any given earthquake."

USGS, Glossary, "Richter scale": "The Richter magnitude scale was developed in 1935 by Charles F. Richter [...] each whole number increase in magnitude represents a tenfold increase in measured amplitude".

USGS, Earthquake Magnitude, Energy Release, and Shaking Intensity: "it represents an 32 times more energy release".

USGS, Glossary, "Seismic moment": "A measure of the size of an earthquake based on the area of fault rupture, the average amount of slip, and the force that was required to overcome the friction sticking the rocks together that were offset by faulting."

USGS, Glossary, "Intensity/Modified Mercalli Intensity Scale (MMI)": "A number (written as a Roman numeral) describing the severity of an earthquake in terms of its effects on the earth's surface and on humans and their structures. [...] There are many intensities for an earthquake, depending on where you are, unlike the magnitude, which is one number for each earthquake."

USGS, Glossary, "Seismic wave": "An elastic wave generated by an impulse such as an earthquake or an explosion. Seismic waves may travel either along or near the earth's surface (Rayleigh and Love waves) or through the earth's interior (P and S waves)."

USGS, Glossary, "Body wave": "A seismic wave that moves through the interior of the earth [...] P and S waves are body waves. Each type of wave shakes the ground in different ways."

USGS, Glossary, "P wave/compressional wave": "a seismic body wave that shakes the ground back and forth in the same direction and the opposite direction as the direction the wave is moving."

USGS, Glossary, "S wave/shear wave": "a seismic body wave that shakes the ground back and forth perpendicular to the direction the wave is moving."

USGS, Glossary, "Surface wave": "A seismic wave that is trapped near the surface of the earth."

USGS, Glossary, "Seismometer/seismograph": "an instrument used to detect and record earthquakes. Generally, it consists of a mass attached to a fixed base. During an earthquake, the base moves and the mass does not."

USGS, Glossary, "Seismogram": "A record written by a seismograph in response to ground motions produced by an earthquake, explosion, or other ground-motion sources."

USGS, The Science of Earthquakes, סעיף "What causes earthquakes and where do they happen?". ההסבר המלא בדף מה זו רעידת אדמה?.

M. Sadeh ועמיתיו, "Crustal deformation along the Dead Sea Transform and the Carmel Fault inferred from 12 years of GPS measurements", Journal of Geophysical Research 117 (2012), B08410, https://faculty.fiu.edu/~swdowins/publications/Sadeh-et-al-JGR-2012.pdf, עמ׳ 1: "the Dead Sea Transform (DST), a 1000 km long continental transform fault forming the tectonic boundary between the Arabian plate and the Sinai sub-plate"; "The principal movement along the DST is left-lateral".

USGS, Glossary, "Fault": "A fracture along which the blocks of crust on either side have moved relative to one another parallel to the fracture."

USGS, Glossary, "Strike-slip fault": "A vertical (or nearly vertical) fracture where the blocks have mostly moved horizontally. If the block opposite an observer looking across the fault moves to the right, the slip style is termed right lateral; if the block moves to the left, the motion is termed left lateral."

USGS, Glossary, "Transform fault": "A special variety of strike-slip fault that accommodates relative horizontal slip between other tectonic elements, such as oceanic crustal plates."

USGS, Glossary, "Fault scarp": "The feature on the surface of the earth that looks like a step caused by slip on the fault."

USGS, Glossary, "Slip": "The relative displacement of formerly adjacent points on opposite sides of a fault, measured on the fault surface."

USGS, Glossary, "Plate tectonics": "The theory supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. Slip on faults that define the plate boundaries commonly results in earthquakes."

USGS, Glossary, "Liquefaction": "A process by which water-saturated sediment temporarily loses strength and acts as a fluid, like when you wiggle your toes in the wet sand near the water at the beach. This effect can be caused by earthquake shaking."

USGS, Glossary, "Tsunami": "A sea wave of local or distant origin that results from large-scale seafloor displacements associated with large earthquakes, major submarine slides, or exploding volcanic islands."

USGS, Glossary, "Paleoseismicity": "Earthquakes recorded geologically, most of them unknown from human descriptions or seismograms. Geologic records of past earthquakes can include faulted layers of sediment and rock, injections of liquefied sand, landslides, abruptly raised or lowered shorelines, and tsunami deposits."