摘要
利用ＣＤＳＮ兰州台的短周期（ＳＰ）地震记录资料，对１９９０年４月２６日青海共和７．０级地震前后发生在该地区的３５个前、余震作了波谱分析工作。结果表明，主震前，共和地区小地震的纵、横波位移谱的拐角频率比值ｆＣ（Ｐ）／ｆＣ（Ｓ）为１．８左右。主震后，拐角频率比下降到１．３左右。１９９５年以后，拐角频率比值又上升到１．５左右。
he spectrums of P and Swaves for 35 fore and aftershocks of the Ms 70 Gonghe earthquake recorded by the short period seismograph at Lanzhou station are analyzed. The corner frequency ratio (fC(P)/fC(S) was about 18 before the mainshock;however,it reduced to 13 after the mainshock,where the fC(P) and fC(S) are the amplitudes of P and S waves displacement spectrum at the corner frequency,respectively.After 1995 the corner frequency ratio backed up to about 15,suggesting the corner frequency ratio can become an index reflecting the stress variation in the earthquake preparation zone.
出处
《地震地磁观测与研究》
1998年第4期30-36,共7页
Seismological and Geomagnetic Observation and Research
