Attenuation of high-frequency P and S waves in south and southeast Tehran using blast data

作者：Farahani Jamileh Vasheghani; Zare Mehdi^*; Cichowicz Artur

来源：Soil Dynamics and Earthquake Engineering, 2012, 40: 99-108.

DOI：10.1016/j.soildyn.2012.03.005

The attenuation of P and S waves caused by quarry blasts in south and southeast Tehran was estimated using the extended coda-normalization method. The analysis used 230 seismic events from quarry blasts recorded in a range of 3-50 km using a network of 13 seismic stations. To estimate the frequency-dependent Q-value, the seismograms were band-pass filtered at the central frequencies (f(i)) of 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 10 and 12 Hz using a phaseless eight-pole Butterworth band pass filter with a bandwidth of f root root 2 to f(i)root 2. We showed that geometrical spreading exponent value (gamma) is a variable depending on the propagation distance. The attenuation parameters were: Q(p)(-1)=(100 +/- 6) x 10(-3) (f(-1) (+/-) (0.07)) and Q(s)(-1)=(73 +/- 2) x 10(-3) (f(-1.06) (+/-) (0.03)) indicating that the strong frequency dependency of Q(p)(-1) and Q(s)(-1) can propose heterogeneity of the medium. The ratio of Q(p)(-1)/Q(s)(-1) obtained in this study is larger than unity and less than 2 for the entire frequency range. Also. Q(s) >= Q(p) indicates that the region is composed of half-saturated rocks.

• 出版日期2012-9