A counterclockwise rotating mantle structure beneath the Eastern Mediterranean: Evaluation based on observational invariance

A counterclockwise-rotating mantle quasi-ring structure (RMRS) centered beneath the island of Cyprus has been established through multifactor geophysical analysis in previous publications. The present paper applies the framework of observational invariance to seismic, gravity, and atmospheric datasets to characterize the internal geometric organization of this structure. The azimuthal distribution of strong earthquakes (M ≥ 6.5) organizes into a stable four-sector (m = 4) pattern with a persistently suppressed quadrant (QSP zone, 210°–270°). This organization is confirmed using distinct data sources by gravity field reconstruction, which reveals a coherent ring geometry bounded by a radially localized transition layer at the maximum of the horizontal field gradient. A consistent cross-channel phase offset φ₀ ≈ 15° is supported by decisive Bayesian evidence (B₁₀ ≈ 9 × 10⁴). The QSP zone corresponds to a region of systematically reduced seismic activity spatially associated with, but not identical to, the transition layer of the gravity field. Within the proposed framework, this region is interpreted as associated with a transition regime exhibiting reduced observable dissipation while preserving an underlying saddle structure. The suppressed sector, transition layer, phase offset, and this decoupling are jointly constrained projections of a single saddle-type reduced dynamics. The four coefficients of the reduced Riccati equation are determined from separate observational channels from three observational channels; their consistency is confirmed by a residual test yielding |ℛ| = 0.157 < σₐ = 0.60, and a verifiable prediction is the transport coefficient ratio ω_GPS/ω_spr ≈ 0.784. Thus, the anomalous rotating mantle structure is characterized from separate observational channels at a new geometric level using the methodology of observational invariance.