Coda Q from educational seismograph network around Koyna-Warna, western India

We computed the coda wave attenuation (Q(C)) using reservoir-induced seismicity of the Koyna-Warna region in the western part of the Indian shield. We analyzed 484 local seismograms recorded by 16 broadband seismic stations at central frequencies 1.5, 3, 6, 12, and 24 Hz for lapse time window lengths 30s, 40s, 50s, and 60s using the single-backscattering method (Aki and Chouet 1975). The results show that spatial variation of Q(C), increases from west to east, and north to south in the study region. Our lapse time-dependent of Q(C) estimates are (138.05 & PLUSMN;37.41)f((1.07 & PLUSMN;0.07)), (191.18 & PLUSMN;45.24)f((1.00 & PLUSMN;0.07)), (240.07 & PLUSMN;61.50)f((0.95 & PLUSMN;0.08)), and (299.42 & PLUSMN;76.32)f((0.88 & PLUSMN;0.07)) for 30s, 40s, 50s and 60s, respectively. The results show that low Q(C) at low frequencies (<3 Hz), which indicates high attenuation at a shallow depth of the region. We compared Q(C) with other regions of the world, as well as in India. Our results are high compared to the earlier studies in the Koyna-Warna region. The frequency-dependent parameter, & eta; is greater than 1, which represents that the study region is seismically active. This study is important for evaluating the source parameters and seismic hazard assessment of the region.