Spatial coda Q fluctuation as a probe for heterogeneous media of Kopili fault zone, Northeast region, India

In recent years, the Kopili fault reported an increase in seismic activity. Coda-wave attenuation and its frequency dependency can be used to examine the seismo-tectonics. Here, we document the regional heterogeneity in the coda attenuation. Present data in this region report Q 0 (value of Q C at 1 Hz) variation from 63 (for 30 s window) to 213 (for 90 s window) and n from 1.330 (for 30 s window) to 0.913 (for 90 s window). These significant fluctuations in the attenuation parameter (Q 0 ) and frequency parameter (n), indicate a velocity inconsistency at depths of 230-270 km. This anomaly may be associated with the anisotropy originates in the asthenosphere-lithosphere transition or asthenospheric mantle at depths of 160-320 km. Accordingly, this concise work comprehensively analyzes reported implications, supported by observational evidences.