Sedimentary and crustal structure beneath Kachchh and Saurashtra regions, Gujarat, India

Strong and distinct Ps conversions from Moho and top sediments characterize the radial receiver functions (RF) estimated for stations in Kachchh basin, while, these for stations in Saurashtra are characterized by a strong Ps conversion from Moho and a weak or absence of Ps conversion from top sediments. The jumping inversion of stacked radial RFs suggest that 1–3 km thick top low velocity sediments (Vp: 1.8–2.5 km/s; σ: 0.28–0.34) and a 39–48 km thick crust (σ: 0.25) (thicker than average Precambrian crust) characterize the Kachchh basin area. While, the crust beneath Saurashtra is characterized by a 0–1 km thick moderate velocity sediments (Vp: 2.0–3.56 km/s; σ: 0.25–0.28) and a north dipping shallow Moho (35–42 km; σ: 0.248). The estimated average crustal σ values from the arrival times of PpPms and PpSms + PsPms phases suggest a relatively stronger crust in Kachchh (σ: 0.22–0.27) in comparison to the crust in Saurashtra (σ: 0.18–0.19). In the epicentral zone of 2001 Bhuj earthquake, the estimated Moho thickness reveals a Moho upwarping (3–5 km change in the E–W direction and a 6–9 km change in the N–S direction) beneath the epicentral zone of 2001 Bhuj earthquake, which might have induced large intraplate stresses to cause the Mw 7.7 earthquake at 23 km depth.