不同震级范围的地震频度和频度比

SEISMIC FREQUENCY AND FREQUENCY RATIO IN DIFFERENT MAGNITUDE RANGE

讨论了云南地区不同震级范围的小震频度在强震前的时间进程曲线,发现在介质比较破碎地区,震级偏小的地震频度显示出较明显的强震前孕震系统的非线性阶段,而在介质比较完整的地区,则震级偏大的地震频度反应较明显。为此,引入了频度比的概念,结果表明,强震孕震区的频度比表现为在强震前2—4年,持续增加或持续降低,在强震前1—2年,呈(增加后)降低或(降低后)增加的异常变化,曲线形态出现拐点。对频度比在实际预报工作中的预报能力。

The time progressing curves of small earthquake frequency in differ ent mag- nitude range before strong earthquake in Yunnan have been in this paper.We find that the seismic frequency of smaller magnitude shows relatively obvious nonlinear stage of seismogenic system before strong earthquake in the area where the medium is rather braken,but the seismic freqency of greater earthquake magnitude does ob- vious in the area where the medium is relatively integrated.Consequently,the con- cept of frequency ratio is introduced.The result shows that the frequency ratio of strong seismogenic region has abnormal variation of increasing or decreasing steady two to four years before the strong earthquake occurred and decreasing(after increasing)or increasing(after decreasing)one to two years before the strong earthquake occurred.The turning point appears in the curve pattern.It is also discussed that the predictability of frequecy ratio in the practical forecast work.