TESTING THE COMPLETENESS OF EARTHQUAKE CATALOGS AND THE HYPOTHESIS OF SELF-SIMILARITY
TESTING THE COMPLETENESS OF EARTHQUAKE CATALOGS AND THE HYPOTHESIS OF SELF-SIMILARITY
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DOI：
10.1038/337251a0
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发表时间：
1989-01-19
期刊：
影响因子：
64.8
通讯作者：
SACKS, IS
中科院分区：
文献类型：
--
作者：
RYDELEK, PA;SACKS, IS
地震过程的自相似性与观测到的线性b值关系log（N）= a-bM是一致的，其中N是M级地震的个数。偏离线性被认为是由于统计波动，因为在大M事件的稀缺性，或从不完整性，因为在小M的检测阈值。在某个震级以上，所有的局部事件都被检测到，因为它们超过了地震图上的噪声背景。然而，随着震级的降低，当地震信号接近噪声背景时，事件就无法被检测到。因此，在夜间记录的最小的地震事件要比在白天记录的多，因为文化噪声源和风在夜间减弱了，从而产生了可能更安静的地震图。在这里，我们使用这种昼夜噪声调制来开发地震目录的完整性测试;目录，表明没有显着的调制被认为是完整的。我们测试了三个目录，并表明，完整性的幅度可以从b值偏离线性的幅度不同。特别是，目录显示显着偏差的线性在smallM，但在其他方面是完整的，是在与地震自相似性的假设。
Self-similarity of the earthquake process is consistent with the observed linearb-value relation log (N) =a – bM, whereNis the number of earthquakes with magnitudeM. Deviations from linearity are believed to be due to statistical fluctuations because of the scarcity of events at largeM, or from incompleteness because of a detection threshold at smallM. Above some magnitude level, all local events are detected, because they exceed the noise background on the seismogram. As magnitude decreases, however, events go undetected as the seismic signal approaches the noise background. Thus more of the smallest events should be logged at night than during the day, because the cultural noise sources and winds are diminished at night, resulting in presumably quieter seismograms. Here we use this day-to-night noise modulation to develop a completeness test for earthquake catalogues; catalogues that indicate no significant modulation are considered complete. We test three catalogues and show that the completeness magnitude can be different from the magnitude at which theb-value departs from linearity. In particular, catalogues that show significant deviations in linearity at smallMbut are otherwise complete, are at odds with the hypothesis of earthquake self-similarity.