Figure 4

(a) CCP imaging along Eil Darrad–Dharyeley transect. Pink inverse triangles show the location of the stations and black-filled circle symbols represent the Moho depths estimated from the H-κ stacking. CCP image reveals a major high-velocity gradient between 20 and 30 km depth (yellow dotted line), which is interpreted as the Moho boundary. A good match is noticed for Moho depths observed from H-κ stacking and CCP imaging beneath Eil Daraad, Hagal and Burao stations, while shallow Moho depths are seen at Haydh Duato and Dharyeley. Due to wide gaps between stations (white gaps), the shallow intra-crustal discontinuities are unresolved. The scale bar represents the amplitude of positive (red) and negative (blue) polarities of arrivals. (b) Two-dimension density model along the transect-A running across Somaliland (see Fig. 1 for location). The Moho depths (black-filled circles) are derived from H-κ stacking and densities of sedimentary column constrained are obtained from drilled wells BD-1 and DS-2, which penetrated the Proterozoic basement at 1,471 m and 1,444 m, respectively. The crustal model suggests an asymmetric sedimentary basin in the Burao region with a maximum depth of 6 km. A sauce-shaped basin with a maximum depth of 2 km is noticed beneath Hagal. Beneath Eil Daraad and Burao, the Moho gets shallower (~ 22 km), and the basement is at a 5–6 km depth. The fit between observed and calculated gravity anomaly is particularly good.