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 ANDRA
French National Agency for Radioactive Waste Management. |
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Asthenosphere
Layer beneath the lithosphere (part of the upper mantle). |
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CEA
Commissariat à l'Energie Atomique (French Atomic Energy Commission). |
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CND
Centre National de Données (French National Data Center, in Bruyères-le-Châtel). |
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COFRAC
COmité FRançais d'ACcréditation (French Committee for Accreditation). |
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CTBT
Comprehensive nuclear Test-Ban Treaty (TICE in French). |
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CTBTO
Comprehensive nuclear Test-Ban Treaty Organization (OTICE in French). |
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DAM
Direction des Applications Militaires (Military Applications Division of the CEA). |
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DASE
Département Analyse Surveillance Environnement (Environmental Assessment and Monitoring Department). |
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Dip
Inclination of a sedimentary stratum, a schistosity plane or a fault relative to horizontal. It corresponds to the measurement of the line of maximum slope of the surface in question. |
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EMSC
European-Mediterranean Seismological Centre (CSEM in French). |
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Epicentre
Point on the earth's surface directly above the focus (hypocenter) of an earthquake. |
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Fault
Zone of fractures or breaks in rocks where movements of more or less severity occur. |
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Focal mechanism
Geometric representation of the rupture that caused an earthquake (orientation and dip of the fault, movement on the fault plane, etc.). |
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Focus
Point (at depth) where an earthquake starts. Synonym: hypocenter. |
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GFZ
GeoForschungsZentrum (German Geoscience Research Center). |
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GPS
Global Positioning System: navigation system based on a constellation of satellites used to retrieve any location worldwide with an accuracy of approximately 10 meters. |
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Hypocenter
Point (at depth) where an earthquake starts. Synonym: focus. |
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IAEA
International Atomic Energy Agency. |
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IDC
International Data Center, in Vienna (Austria). |
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IMS
International Monitoring System. |
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Isoseismal Line
Line connecting points on the Earth's surface at which earthquake intensity is the same. |
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Lithosphere
Outer, rigid shell of the Earth above the asthenosphere. Its thickness, which may be just a few kilometers beneath the oceanic crust, increases to 150 km beneath the continents. It is divided into plates moving in relation to each other. |
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Magnitude
The magnitude of an earthquake is a dimensionless parameter for estimating the amount of energy released. Not to be confused with seismic intensity which measures surface damage. Two earthquakes with the same magnitude can have different maximum intensity, and vice versa. |
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Magnitude Mb
Magnitude of body waves calculated from the amplitude and period of primary body waves (P-waves). |
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Magnitude ML
Local magnitude calculated from the amplitude and period of secondary body waves (S-waves). |
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Magnitude Mm
Mantle magnitude calculated from long-period surface waves (Rayleigh and Love waves). |
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Magnitude MS et Ms
Magnitude of surface waves calculated from the amplitude and period of surface waves (Rayleigh waves), around 20 seconds. |
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Magnitude Mw
Moment magnitude calculated from the seismic moment. |
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Mini-network
Better detection capability is achieved by seeking correlations between signals. A mini-network comprises several stations uniformly located around a central point. The distance between each station is roughly the length of the expected signal wave. Depending on the wave type, this length can range from 100 meters to 10 kilometers for seismic stations and be approximately 1 km for infrasound stations. |
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Moment (seismic)
Unlike magnitudes, a seismic moment Mo is based on a physical seismic source model. This model corresponds to a physical slip of the lips of a fault, without any opening or closure (double torque model). One of the torques corresponds to a break in the fault. It is defined by Mo = mu.S.D, where mu is the rigidity of the material, S is the surface of the fault, and D, the mean fault slip (or throw). Its unit is Newton.meter (Nm). |
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NPT
Non-Proliferation Treaty. |
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P-waves and S-waves
Body waves (propagating inside the earth). Historically, the P comes from "primary" and S from "secondary". The P-waves therefore arrive first and the S-waves second. In terms of physics, P-waves are longitudinal waves (or compression waves) with a velocity of about 6 km/s in the crust and 8 to 13 km/s in the mantle. S-waves are transverse waves (or shear waves) and propagate only in solid materials. |
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Plate tectonics
Theory in which the lithosphere is divided into a number of plates that interact with one another at their boundaries, causing seismic and tectonic activity along these boundaries. |
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PMCC
Progressive Multi Channel Correlation: automatic mini-network recording processing method, developed by CEA/DASE. |
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Rayleigh waves and Love waves
Surface waves (waves guided by the crust-atmosphere interface). Rayleigh waves are vertically polarized (like ocean swell), Love waves are horizontally polarized. |
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Risk (seismic)
Probability of an earthquake occurring and causing damage to infrastructures or people within a given area. |
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RMS
Root Mean Square. |
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Schistosity
Particular texture of a rock caused by crushing and manifested by a centimeter- or millimeter-scale layered structure, perpendicular to tectonic pressures, in the axial plane of the folds that are formed. |
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Seismic hazard
Probability of earthquake occurrence in a given area. |
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Seismic intensity
Seismic intensity estimates the damage caused by earthquakes, which depends on the type of ground, depth of the earthquake and type of constructions. The further away the epicenter, the weaker the seismic intensity. Not to be confused with magnitudes, which represent the energy released by an earthquake. |
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Seismotectonics
Identification of tectonic events which give rise to seismic activity. |
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SOFAR
The SOFAR (Sound Fixing And Ranging) channel is a virtual underwater channel. Here hydroacoustic waves are trapped and propagate without interacting with the ocean bed or surface, and therefore with no energy loss for thousands of kilometers. |
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Tectonics
All the various deformations suffered by the existing geological. |
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TREMORS
Tsunami Risk Evaluation through seismic MOment from a Real-time System: strong earthquake alert system designed and produced by CEA/DASE for tsunami prevention. |
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Tsunami
Seismic sea wave. Comes from Japanese origin of "tsu" (harbor) and "nami" (sea wave). |
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Two-way nesting
Broadly speaking, the mesoscale model principle is based on the solution of meteorology equations in nested domains with different resolutions, grouped into "levels".
Information is exchanged from one level to another via boundaries (in the form of boundary conditions) to higher resolution, while feedback to the calculation at lower resolution involves the entire domain via interpolation techniques.
This type of method is sometimes called "two-way interaction" or "two-way nesting" in contrast to the "one-way nesting" method, which does not allow feedback to the upper level. |
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USGS
United States Geological Survey. |
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UT
Universal Time. |
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