震源系统小震调制比(rm)和异常面积(Srm)起伏加剧的时空特征与强震的中、短期预报

THE TIME-SPACE CHARACTERISTICS OF rm AND Srm FLUCTUATION INTENSIFICATION IN THE EARTHQUAKE SOURCE SYSTEM AND THE MID-SHORT-TERM STRONG EARTHQUAKE PREDICTION

摘要:

本文对强震前震源系统的调制比r_m和调制比异常面积Sr_m随时间变化的起伏加剧现象进行回顾性研究,得到下列研究结果:
(1)强震前近源区以及中强震前近源区大多出现调制比r_m的起伏加剧,并大多在起伏频次达三次时有大震或中强震发生。
(2)大多数中、强地震前r_m异常面积Sr_m围绕震源区呈现由小至大、由大至小的过程,因此引入最小异常面积Sr_min和最大异常面积Sr_max之比γ作为中、短期预报指标,根据统计得到异常指标[γ]如下式
γ=Sr_min/Sr_{max,γ=0.32±0.09
某些震例在震前出现异常面积Srm起伏的加剧过程,初步认为是震源区周围调整单元调整能力较差导致的结果。
(3)rm、Srm起伏加剧开始时间与震级有关,震级愈大,起伏加剧出现愈早。根据半年步长逐月滑动得到的rm-Ｔ图,起伏加剧开始至发震的时间与震级M的统计,得到如下关系(Ｔ以月计)
M＝4.29＋0.11Ｔ
(4)强震前场区异常一般呈现随机异常型、波动型和衰减型三种。若场区某统计区出现rm的三次起伏加剧时,说明该统计区未来有强震发生。
(5)由自治系统和非自治系统原理初步解释了震前震源区周围调整区调制比rm及调制比异常面积Srm起伏现象的周期特征。}

Abstract:

By studying the fluctuation intensification of the ratio of small earthquakes modulated (r_m)and the abnormal area of the ratio of small earthquakes modulated (Sr_m) in the earth-quake source system before strong earthquakes. The following results are gained:
1.The fluctuation intensification of the ratio of small earthquakes modulated almost appears before strong earthquakes in the source and near source region or before medium earthquakes in near source region and when the fluctuated times are three, the strong earthquake or mediutn earthquake will happen.
2.r_m abnormal area (Sr_m) around source region shows the process from small to largearea and then, from large to small area before most.moderate earthquakes,therefore,we take the ratio of the minimum area of r_m anomaly to the maximum area of r_m anomaly as an index of the mid-short term earthquake prediction,according to statistics,the anomaly index[λ]is
λ=Sr_min/Sr_max,[γ]=0.32+0.09
In some earthquakes,the Sr_m fluctuation intensification appears before earthquakes,this may be regarded as the result of weak adjusting ability of adjustment units around the source region.
3.The beginning time of r_m and Sr_m fluctuation intensification has a connection with magnitude of earthquake,the bigger the magnitudes are,the earlier the fluctuation intensi-fication will appear.According to the statisties of the time (t) from the beginning of Sr_mfluctuation intensification to earthquake occurrence and magnitude (M),the following for-mula is obtained:
M=4.29+0.11t±0.33
4.There ordinarily appear three forms of r_m anomalies in the field region before strong earthquakes:random,fluctuating and declining.If there are three r_m fluctuation intensifica-tions, the strong earthquake will happen in the field.
5.By using the principle of autonomous system and unautonomous system,the fluctu-ation of r_m and Sr_m adjustment region around the source before earthquake is explained briefly.