【摘要】 本文利用中国数字地震台网(CDSN)短周期垂直向的直达 P 波数字资料,通过频谱分析的方法,测定了3个5级左右的中强地震及其随后小地震的应力降和介质 Q 值。初步研究了不同类型的中强地震在这方面的差异。并指出,中强地震的应力降低,与随后发生的小地震的平均应力降比值也小时,有可能在震中附近还会发生更大的地震。相反,中强地震的应力降高,与小地震的平均应力降的比值大时,随后发生更大地震的可能性就小。同时还指出,中强地震发生前,往往介质 Q 值部较低。这在中强地震发生后,对及时估计地震趋势有一定的实用价值.更多还原

【Abstract】 In this article, by using the CDSN digital data of vertical compment ofshort-period direct P wave through spectral analysis method, the author hasdeterminated the stress drop and the medium Q value for three moderate earth-quakes with magnitudes about 5.0 and their following small sequential earthquakes.He has preliminarily studied the differences in those aspects among different typesof moderate earthquakes, and pointed out that if the stress drop of a moderateearthquake is small and their ratio of it to the average stress drop of smallsequential earthquakes is also small, the probability of the occurence of a stillstronger earthquake near the epicenter is large. On the contrary, when the stressdrop of the moderate earthquakes is large and the ratio of it to the average stressdrop of small sequential earthquakes is also large, the probability of the occuren-ce of a strong earthquake is small.He has also pointed out that the medium Qvalue is always low before moderate earthquake occurs. Such phenomena have certainpractical usage for estimating the tendency of the earthquake sequence after theoccurence of a moderate earthquake.更多还原