| 23 Sep 2025
Constraining the depth of the lithosphere-asthenosphere boundary in tectonically complex regions using locally adjusted lithological forward models and seismic velocities
Abstract. In this study, we employ 1D migration of S-to-P receiver functions to determine the lithosphere-asthenosphere boundary (LAB) depth beneath 41 seismological stations in the Pannonian Basin (Hungary). Our approach incorporates forward models of seismic velocity profiles tailored to local lithospheric structures, allowing for an improved constraint on LAB depths in comparison with global velocity models.
We systematically evaluate the impact of crustal structure, mantle composition, temperature variations, and partial melt on seismic velocities. Global velocity models, while effective for large-scale studies, have significant limitations in resolving lithospheric-scale structures due to their coarse parameterization. Our forward models incorporate variations in sedimentary layer velocities, Moho depth, and LAB-associated velocity reductions, leading to LAB depth estimates that differ from those derived using the IASP91 model. Notably, 1 vol.% partial melt below the LAB results in a pronounced velocity decrease, whereas metasomatism and volatile-bearing phases may cause localised velocity reductions but have limited effect on the determination of LAB depths.
LAB depths obtained using local versus global velocity models reveal a strong correlation, yet notable discrepancies exist at stations with complex lithospheric structures or thick sedimentary cover, as further supported by anomalies in surface heat flow data. Our results demonstrate that locally calibrated seismic velocity models offer a more accurate representation of the lithosphere-asthenosphere transition than global models, particularly in regions with complex tectonic and thermal histories. Integrating geophysical and petrological approaches is key when investigating lithospheric structure, as well as the combined interpretation of different factors that shape seismic LAB signatures.
I read the manuscript "Constraining the depth of the lithosphere-asthenosphere boundary in tectonically complex regions using locally adjusted lithological forward models and seismic velocities" by Nóra Liptai and colleagues with pleasure and great interest.
From my point of view, the work is well-conceived, clearly written, and well-structured, addressing an important topic in in lithospheric studies through an interdisciplinary approach that combines seismological, petrological, and thermal perspectives. The authors make a solid effort to constrain the LAB depth beneath the Pannonian Basin using locally calibrated velocity models, and to me the paper provides valuable insights into how compositional and thermal variations affect seismic signatures of the LAB in this area.
Although my expertise lies mainly in the field of receiver function analysis, and therefore the majority of my comments concern the methodological aspects of the study, I found the discussion of petrological and thermal factors convincing and generally well supported by the existing literature. In general, I believe the paper represents a meaningful contribution to the understanding of the lithosphere-asthenosphere boundary and deserves publication after minor revisions.
I attach my detailed comments (both for manuscript and figures) and line-by-line suggestions in the PDF attached.