The Southern Zagros Collisional Orogen: New Insights From Transdimensional Trees Inversion of Seismic Noise

S. Pilia , J. A. Jackson , R. Hawkins (1) , A. Kaviani , M. Y. Ali

1 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement

Imaging and resolving the lateral continuity of 3-D crustal structures enhance our ability to interpret seismicity and to understand how orogens are created. We apply a Bayesian, hierarchical inversion approach based on a transdimensional trees-structured wavelet parameterization to recover phase velocity maps at 2-40 s periods. We then invert phase velocity dispersion to constrain a 3-D shear velocity model of the crust beneath south-central Iran. Together with accurate earthquake centroid depths and focal mechanisms, the pattern of 3-D velocity variations supports recent suggestions that most large earthquakes in the Zagros occur within the lower sedimentary cover or close to the sediment-basement interface. Furthermore, we find evidence for Arabian basement underthrusting beneath central Iran, although only in one location does it appear to generate earthquakes. Our new 3-D tomographic model clarifies and throws new light on the crustal structure of the SE Zagros and its relation to seismicity and active faulting.

Keywords: Zagros; seismicity; transdimensional tomography; continental underthrusting

Domains: Sciences of the Universe [physics]

S. Pilia, J. A. Jackson, R. Hawkins, A. Kaviani, M. Y. Ali. The Southern Zagros Collisional Orogen: New Insights From Transdimensional Trees Inversion of Seismic Noise. Geophysical Research Letters, 2020, 47, ⟨10.1029/2019GL086258⟩. ⟨insu-03710134⟩