HIGHLY ACCURATE ABSORBING BOUNDARY CONDITIONS FOR WIDE-ANGLE WAVE EQUATIONS

Abstract

We develop a new class of absorbing boundary conditions (ABCs) to prevent unwanted artifacts and wraparounds associated with aperture truncation in migration/modeling using high-order, one-way wave equations. The fundamental approach behind the proposed development is the efficient discretization of the half-space, beyond the boundary of interest, using midpoint-integrated imaginary finite elements, an idea recently utilized in the development of effective one-way wave equations. The proposed absorbing boundary conditions essentially add absorbing layers at the aperture truncation points. We derive the absorbing boundary conditions, analyze their properties, and develop a stable explicit finite-difference scheme to solve the downward-continuation problem modified by these boundary conditions. With the help of numerical examples, we conclude that with as few as three absorbing layers, i.e., two additional gridpoints, the waves can be absorbed completely, thus preventing associated artifacts. © 2006 Society of Exploration Geophysicists.