We study anisotropy of P-wave attenuation that is Q-anisotropy, and develop an approach named QVOA (seismic quality factor Q versus offset and azimuth) to estimate the fracture-strike direction identified by the azimuth ϕ0. We derive QVOA formula Q^-1(θ, ϕ) for the P-wave attenuation Q^-1 as a function of the polar angle θ and azimuth ϕ, and test Q^-1(θ,ϕ) using physical modeling data. Our testing consists of fitting a function Q^-1(θ, ϕ) to the data from the physical modeling, using the method of least squares. The QVOA-formula gives the most accurate estimation of the direction ϕ0 of the HTI-symmetry axis in comparison with other approximation formula. The values of velocity and attenuation are, in some sense, reciprocals of each other: the attenuation is greatest in the direction of the HTI-symmetry axis ϕ0=0°, where the velocity is least, and vice versa at the orthogonal direction ϕ=90°, which is the fracture-strike direction. That is, the azimuth of the minimal attenuation ϕ=90° coincides with the direction of the fracture strike (ϕ=90°), where the velocity is maximal.