摘要
本文根据Ｋ．Ａｋｉ（１９８０）提出的ω平方、常应力参数谱衰减模式．研究了地面运动速度谱衰减的带宽效应，导出了用速度谱直接估算地震矩Ｍ０的新方法。利用中日合作在滇西地震预报实验场区的洱源、脉地、松桂三个地区新获得的三次微震群序列数字化记录资料，通过不同参数Ｑ值和△σ值的计算比较，选取Ｑ＝３００，△σ＝１．０ＭＰａ作为测定的参数值，计算了Ｐ波和Ｓ波速度谱的理论量板，并且与实际观测点的低频速度谱值相比较，用这样的方法测定了三次震群序列的地震矩Ｍ０和震源参数。结果给出，在震级为１．０～２．５级的范围内，地震矩Ｍ０＝１０（１０）～１０（１３）（Ｎ·ｍ），震源破裂半径ａ＝７０～２００（ｍ），Ｐ波和Ｓ波的拐角频率比ｆ（ｏｐ）／ｆ（ｏｓ）＝１．５８。用Ｐ波或Ｓ波三分量的速度谱值测定的地震矩比较一致，以及在相同震级范围内，用速度谱方法测定的结果与其它方法测定的结果也基本一致。本文提出的速度谱测地震矩的方法是一种简便实用的方法，当地震矩和观测低频谱值（如ｆ＝１．０ＨＺ）已知时，可通过查函数表值快速测定Ｍ０值。
According to the source velocity spectra model of the ω2 and constant stress parameters by K. Aki (1980), the bandwidth effect of the ground motion velocity spectra attenuation was studied. We have derived a newly method using the velocity spectra to measure directly the seismic moment M0. Based on the some new digital data of the three microearthquake sequences occurring at Er' yuan, Maidi and Songgui area respectively, which were obtained by near-field observatiob in Westren Yunnan Earthquake Prediction Study Area (WYEPSA), on OCtober 1991, China and Japan cooperate with each other, here we took Q=300 and △σ=1. 0MPa as the reference value, through different parameters Q and △σ values calculated, compared with the between velocity spectral theoretiCal curves and observation low frequency spectral value (1. 0Hz) of P and S waves at observation point. Using this method, the seismic moment M0 and source parameters of the above three earthquake sequences have been measured. Result of the study shows the M0 is 10(10)-10(13) (N·m),the source rupture radius a=70-200 (m), for ML=1. 0-2. 5, and the ratio f(op)/f(os)=1. 58. We found from the results of M0using P and S wayes to measure are less difference, which those results are in accord with that of the another methods for the same magnitude range, this is a simple and convenient method, then the seismic moment M0 can be quickly detemine directly from the function tables of the velocity spectra if we were knew the epicentral distance and observation low frequency spectral (f=1. 0Hz) values.
出处
《高原地震》
1995年第1期1-18,共18页
Plateau Earthquake Research
关键词
峰值速度谱
地震矩测定
微震序列震源参数
滇西地区
Peak velocity spectra
Seismic moment determination
Microearthquake sequence Parameters
Western Yunnan area
