Normal moveout (original) (raw)
動校正（英語：normal moveout）又稱正常时差校正，是指地震波传播时间從炮检距為零的法线反射到炮检距增加時的反射之間的時差。地震波传播时间從地下界面反射的地面檢波器最短的是垂直方向，又稱法线反射。當檢波器遠離炮點時（炮检距）增加時，其反射時間會增加。反射時間按炮检距增加的時間曲线爲時距曲綫，若反射界面是水平，其時距曲綫是双曲线形状。關係如下 其中 為炮检距等於零時反射時間，x为炮检距，v为反射界面上覆层波速。 地下界面須由法线反射时间代表其形态。故非法线反射需校正到法线反射，校正值計算如下： 為校正值。 由計算公式可看出，同一深度反射界面（及v 不變）。由于各接收点距激发点远近不同（炮检距），校正量也不同，故称动校正。同樣，若不同深度（v）的反射界面、其校正量也不同。 除了速度和炮检距外，校正值也受其它因素的影響，包括反射界面傾角以及其方位角與激发点和檢波器的方位角的關係.
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| dbo:abstract | In reflection seismology, normal moveout (NMO) describes the effect that the distance between a seismic source and a receiver (the offset) has on the arrival time of a reflection in the form of an increase of time with offset. The relationship between arrival time and offset is hyperbolic and it is the principal criterion that a geophysicist uses to decide whether an event is a reflection or not. It is distinguished from dip moveout (DMO), the systematic change in arrival time due to a dipping layer. The normal moveout depends on complex combination of factors including the velocity above the reflector, offset, dip of the reflector and the source receiver azimuth in relation to the dip of the reflector. For a flat, horizontal reflector, the traveltime equation is: where x = offset; v = velocity of the medium above the reflecting interface; = travel time at zero offset, when the source and receiver are in the same place. According to W. Harry Mayne, inventor of the Common Point Reflection Method in 1950, in order to avoid the "smearing" of recorded seismic data caused by the use of geophone sensor arrays, I needed a very long array to attenuate the noise, yet each point of the array needed to represent the same reflection point of the subsurface. For a non-dipping reflector, this meant that the source and receiver station would have to move the same distance-in opposite directions-from the reflection (or mid-) point. One problem still remained. The reflections had different traveltimes on each pair of sources and receivers, so it would be necessary to correct for these differences (moveouts) prior to array formation." Coupled with the normal moveout correction, Mayne stated, "the method was primarily intended to attenuate systematic surface noise, and to average out near-surface aberrations in travel paths. It was soon realized, however, that it alone could also substantially attenuate the insidious multiple reflection." (en) 動校正（英語：normal moveout）又稱正常时差校正，是指地震波传播时间從炮检距為零的法线反射到炮检距增加時的反射之間的時差。地震波传播时间從地下界面反射的地面檢波器最短的是垂直方向，又稱法线反射。當檢波器遠離炮點時（炮检距）增加時，其反射時間會增加。反射時間按炮检距增加的時間曲线爲時距曲綫，若反射界面是水平，其時距曲綫是双曲线形状。關係如下 其中 為炮检距等於零時反射時間，x为炮检距，v为反射界面上覆层波速。 地下界面須由法线反射时间代表其形态。故非法线反射需校正到法线反射，校正值計算如下： 為校正值。 由計算公式可看出，同一深度反射界面（及v 不變）。由于各接收点距激发点远近不同（炮检距），校正量也不同，故称动校正。同樣，若不同深度（v）的反射界面、其校正量也不同。 除了速度和炮检距外，校正值也受其它因素的影響，包括反射界面傾角以及其方位角與激发点和檢波器的方位角的關係. (zh) |
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| rdfs:comment | 動校正（英語：normal moveout）又稱正常时差校正，是指地震波传播时间從炮检距為零的法线反射到炮检距增加時的反射之間的時差。地震波传播时间從地下界面反射的地面檢波器最短的是垂直方向，又稱法线反射。當檢波器遠離炮點時（炮检距）增加時，其反射時間會增加。反射時間按炮检距增加的時間曲线爲時距曲綫，若反射界面是水平，其時距曲綫是双曲线形状。關係如下 其中 為炮检距等於零時反射時間，x为炮检距，v为反射界面上覆层波速。 地下界面須由法线反射时间代表其形态。故非法线反射需校正到法线反射，校正值計算如下： 為校正值。 由計算公式可看出，同一深度反射界面（及v 不變）。由于各接收点距激发点远近不同（炮检距），校正量也不同，故称动校正。同樣，若不同深度（v）的反射界面、其校正量也不同。 除了速度和炮检距外，校正值也受其它因素的影響，包括反射界面傾角以及其方位角與激发点和檢波器的方位角的關係. (zh) In reflection seismology, normal moveout (NMO) describes the effect that the distance between a seismic source and a receiver (the offset) has on the arrival time of a reflection in the form of an increase of time with offset. The relationship between arrival time and offset is hyperbolic and it is the principal criterion that a geophysicist uses to decide whether an event is a reflection or not. It is distinguished from dip moveout (DMO), the systematic change in arrival time due to a dipping layer. (en) |
| rdfs:label | Normal moveout (en) 動校正 (zh) |
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