Coda Q Estimates of the Bilaspur Region of Himachal Lesser Himalaya

The present study employs the single backscattered model proposed by Aki and Chouet (J Geophys Res 80:3322–3342, 1975) to assess the quality factor (Q) of coda waves within the Bilaspur region of the Himachal Lesser Himalaya. The investigation focuses on the attenuation of seismic waves within the frequency range of 1.5–24 Hz, utilizing coda waves from 94 local events located within 100 km of the region and exhibiting a magnitude of (0.15M_L3.03). These events were captured by a five-station seismological network centered on the digital station Sikandra (SKND) during the period spanning May 2008 to April 2011. Specifically employing the vertical component records, the HYPOCENTER computer program was utilized to determine hypocenter parameters for these events. The MATLAB algorithm established for estimating Coda Q (Qc) adheres to the specifications of SEISAN’s CODAQ function. In the analytical process, waveforms possessing a signal-to-noise ratio (SNR) of at least 5 were selected. Examination of coda waves encompassing frequencies from 1.5 to 24 Hz, within a 30-second time window, yielded Qcvalues ranging from 155 at 1.5 Hz to 3781 at 24 Hz. This illustrates the frequency-dependent nature of Qc, which increases with rising frequency. The Q-frelation for the entire region is derived as Qc=105f1.14. This Qc estimation characterizes the average attenuation properties of the medium across an approximately 21,899 sq. km region, with lateral dimensions of 204 km and vertical dimensions of 102 km. When contrasting the observed Qc relationship with those from other seismically active regions of India, it becomes evident that the estimated Qcvalue within the Bilaspur region of the Himachal Himalaya is notably higher, signifying greater seismic activity in comparison to other such areas in India.