Regional moment tensor estimation with 3-D velocity models—Application to the 2017 Hojedk, Iran sequence and performance assessment
Year: 2026
Type: article
Abstract: SUMMARY We estimated seismic moment tensors (MTs) for the 2017 magnitude M6 Hojedk, Central Iran, earthquake triplet and their aftershocks, employing 1-D and 3-D regional and global velocity models to evaluate source parameter stability and resolution fitting in-country waveform data. We used the Moment Tensor Uncertainty Quantification (MTUQ) software, which performs a grid search for MT estimation and uncertainty analysis. For the regional 3-D velocity model, we used MEAD-M20, a full-waveform inversion model of the Middle East derived from fitting 15-s body waves with 30-s body and surface waves. We compared the regional 1-D- and 3-D-based results with an existing data base of deviatoric MT solutions, and for both regional velocity models, we found good agreement. However, for periods T ≥ 25–30 s and events with moment magnitudes Mw ≥ 4.5, the 3-D regional synthetic seismograms outperformed the 1-D regional model, reducing waveform misfits, time-shifts and non-double-couple contributions. We consider non-double-couple contributions spurious and their reduction an improvement, as previous studies of the sequence found predominantly shear faulting on reverse faults. Furthermore, uncertainty analysis shows that the moment tensor, non-double-couple component, magnitude and depth are more tightly constrained for the 3-D model. The current 3-D model shows no clear improvements relative to the 1-D model in terms of misfit, time-shifts and non-double-couple contributions at short periods T ≈ 15-25 s relevant for modelling smaller events. Using the regional models results in lower misfits and tighter constraints on the MT solutions than with the global 1-D PREM and the 3-D S2.9EA models. Improved MT estimation and parameter resolution for moderate-to-large events using in-country data validate the recently developed 3-D Middle East velocity model. Further model refinements are needed to model shorter period data required to analyse and improve the resolution of smaller (M ≤ 4) seismic events. Such improvements are within reach by using available in-country data and well-constrained MT solutions from a regional moment tensor data base.
DOI: 10.1093/gji/ggag244
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,416
Funder: National Science Foundation
OpenAlex ID: W7166004601