Translations:Seismic interpretation - book/7/en

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What is an event? Look at a crowd of people walking down the street. Their strides have similarities, but the people are not in lockstep. Suppose, however, that small group is marching in step. They stand out. Now look at a record of raw seismic traces. Generally, one trace is somewhat similar to the next. However, suppose that in at a given instant of time (i.e., the arrival time), the traces abruptly line up (i.e., become coherent) so that the peak (or valley) of one trace becomes quite similar in shape and character to the peak (or valley) of the next trace. Such a lineup of traces in lockstep is called an event. An event indicates the arrival of new seismic energy. Generally, the lineup is along a slanting line, the slope of which indicates the stepout time of the arrival of energy. An event can reveal a reflection, refraction, diffraction, or other type of wavefront arriving at a sensor.