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We present a comprehensive analysis of the formation and evolution of afan-spine-like configuration that developed over a complex photosphericconfiguration where dispersed negative polarity regions were surrounded bypositive polarity regions. This unique photospheric configuration, analogous tothe geological "atoll" shape, hosted four homologous flares within itsboundary. Computation of the degree of squashing factor (Q) maps clearlyrevealed an elongated region of high Q-values between the inner and outerspine-like lines, implying the presence of an hyperbolic flux tube (HFT). Thecoronal region associated with the photospheric atoll configuration wasdistinctly identified in the form of a diffused dome-shaped bright structuredirectly observed in EUV images. A filament channel resided near the boundaryof the atoll region. The activation and eruption of flux ropes from thefilament channel led to the onset of four eruptive homologous quasi-circularribbon flares within an interval of $\approx$11 hours. During the interval ofthe four flares, we observed continuous decay and cancellation of negativepolarity flux within the atoll region. Accordingly, the apparent length of theHFT gradually reduced to a null-point-like configuration before the fourthflare. Prior to each flare, we observed localised brightening beneath thefilaments which, together with flux cancellation, provided support for thetether-cutting model of solar eruption. The analysis of magnetic decay indexrevealed favourable conditions for the eruption, once the pre-activated fluxropes attained the critical heights for torus instability.

Successive occurrences of quasi-circular ribbon flares in a fan-spine-like configuration involving hyperbolic flux tube