The topical issue has been derived from Symposium GD2.4/SM4.1/TS10.2 The Lithosphere-Asthenosphere Boundary (LAB) Dilemma during the EGU 2011 Assembly. We encourage scientists to submit their results achieved in interdisciplinary studies of the LAB, especially petrological and dynamical modelling including asthenosphere–lithosphere interaction in geodynamic processes. In the volume we will bring together scientific achievements from all fields in Earth sciences to incorporate the current status and advancements in the studies of the LAB. We especially invite contributions from authors who were not at EGU to submit papers to the special issue on LAB and to the lithosphere and asthenosphere structures.

The lithosphere–asthenosphere boundary is the most extensive and active plate boundary on Earth. However, it is a relatively cryptic boundary compared to other first-order structural subdivisions of Earth. Though we face different physical definitions of the LAB in dependence on methods used to map the boundary, a general understanding "WHAT is the LAB" is still missing. There seem to be several "boundaries", namely the LAB-S (seismological), the LAB- M (mechanical), the LAB-T (thermal), the LAB-C (chemical) and the LAB-E (electromagnetic), all called "LAB" by the colleagues from the particular fields in Earth science.

It is evident that only a multi-disciplinary approach, bringing together all disciplines from Earth sciences, will help us to shed light on the above questions, and to better understand and communicate between the different fields in Earth sciences, what the lithosphere–asthenosphere boundary is all about, what its origin is and what role it has played and still plays in the evolution of our planet.