The two faces of emerging wavefronts

What is it about?

Seismic data stacking has been routinely employed since its advent over 50 years ago and still remains one of the most robust and trusted processing steps. Rather recently, the stacking trajectories have been extended to resemble the signatures of wavefronts emerging at the surface. Based on a duality exposed in the 1980s, we show that these wavefront signatures can be expressed by two different mechanisms to account for heterogeneity that are both intuitive and physically justified. In addition, we demonstrate that this dual nature can be exploited systematically to arrive at new applications that a single approximation would not permit.

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Why is it important?

The concept of curved wavefronts in stacking is still relatively new. This work shows that these new approximations share the same dual characteristics and incorporate the conventional trajectories naturally as subsets. Therefore, they are more general and allow for novel applications such as the identification of multiple reflections and diffractions, or the estimation of the excitation time of a passive seismic source, solely based on traveltime differences observed at different stations.