Content

$$\tag{Content}\label{Content}$$

• \( \ref{Publications} \)
• \( \ref{Abstracts&Presentations} \)
• \( \ref{Thesis} \)
• \( \ref{Technical reports} \)
• \( \ref{Proposals} \)
• \( \ref{Activity reports} \)

$$\tag{Peer-reviewed publications}\label{Publications}$$

Publications

• Beller S., Mohammadi N., Monteiller V. & Operto S., 2023. Crustal and upper-mantle seismic imaging of the Alpine arc from full-waveform inversion of first P-wave teleseismic phases recorded by the AlpArray experiment, in preparation, to be submitted to the Geophysical Journal International.

$$\tag{Abstracts & Presentations}\label{Abstracts&Presentations}$$

Abstracts & Presentations

2022 AlpArray workshop

• Mohammadi, N., Beller, S., Monteiller, V., and Operto, S.: 3D high-resolution imaging of lithospheric VP, VS, and density structure in the Alps using full-waveform inversion of the teleseismic P waves (Poster, PDF) .

EGU 2023, Vienna

• Beller, S., Mohammadi, N., Monteiller, V., and Operto, S.: Preliminary 3D isotropic full-waveform inversion model of the Alpine lithosphere from assimilation of AlpArray teleseismic body waves, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6772, https://doi.org/10.5194/egusphere-egu23-6772, 2023.

Abstract (PDF), Slides (PDF).

The Alps, which result from the convergence between the African and Eurasian plates, are an ideal natural laboratory to study the dynamics and evolution of continental orogens. This mountain range is indeed well documented both by geology and geophysics, which have notably allowed to highlight the different stages of continental subduction and collision during its formation. Nevertheless, large uncertainties remain about the 3D shape of structures and the internal composition of the Alps at crustal and upper mantle scales. This context motivated the European initiative AlpArray which deployed a dense array of more than 600 seismic sensors in the Alps an its periphery paving the way for the application of advanced seismic imaging techniques such as teleseismic waveform inversion (FWI). FWI is becoming a state-of-the-art method for lithospheric imaging as it allows the determination of various subsurface properties (seismic wavespeed, density, anisotropy or even attenuation) with high resolution and accuracy. In this study, we present the preliminary results of the LisAlps project which aimed at applying teleseismic FWI to the AlpArray dataset to build isotropic and anisotropic high-resolution seismic models of the Alps from the surface down to the transition zone. Our preliminary application successfully built a isotropic (P and S seismic wave-speeds and density) model of the entire Alpine lithosphere from the assimilation of the first 60 s of the direct P waveforms of 18 teleseismic events within a period band ranging from 30 to 10 seconds. The resulting models recover large crustal structures of the Alpine range. In the crust, it recovers the surroundings sedimentary basins, crustal thickening in the internal part of the Alps as well as crustal thinning in the Ligurian sea and in the Ivrea zone. In the upper-mantle, where only the P wave-speed model is currently resolved, our model recovers large-scale mantle structures of the European and Apennines slabs.

• Mohammadi, N., Beller, S., Monteiller, V., and Operto, S.: 3D high-resolution imaging of lithospheric VP, VS, and density structure in the Alps using full-waveform inversion of the teleseismic P waves, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13742, https://doi.org/10.5194/egusphere-egu23-13742, 2023.

Abstract (PDF) , Poster (PDF)

The convergence between the African and European plates has created the magnificent Alpine chain with a very complex geological structure. This natural laboratory helps researchers to decipher the geotectonic processes imposed on the region. One useful way to understand better the prevailing geodynamics system is to interpret high-resolution crustal and upper-mantle models developed by full wavefield tomographic methods simultaneously. The high density of broadband stations deployed during the AlpArray project allows us to apply Full Waveform Inversion (FWI) on the teleseismic earthquakes recorded in the Alpine region. FWI minimizes the misfit between the entire recorded and simulated seismograms to reconstruct multiparameter models of the Earth’s interior with a resolution close to the wavelength. We used 203 teleseismic earthquakes with 6.8≤MW≤7.4 and 8≤depth≤630 km recorded by 1232 stations including permanent seismological broadband stations and AlpArray temporary seismic network. To model the propagation of the teleseismic wavefields through the target area, we used a hybrid technique that couples a global wavefield computed by AxiSEM in axisymmetric Earth from the source to the boundaries of the study area to regional wavefield propagating through the lithospheric domain computed by SPECFEM3DCartesian. This target-oriented wavefield injection method mitigates the computational cost of the wavefield simulation at the global scale, hence making high-frequency wavefield simulations in the lithospheric target possible (up to the 1Hz period). We use the AK135 velocity model as the initial model and iteratively inverted the band-pass filtered data at 10-30 s periods using the limited-memory BFGS optimization algorithm to obtain a 3D high-resolution elastic V_P, V_S, and density model for the crust and upper mantle of the entire Alpine chain. Our results show that the main documented structures of the Alps have been recovered well in the crust and upper mantle and confirm that a reliable geotechnical interpretation in the Alps depends on the consideration of the geodynamical process on Apennine and Dinaric simultaneously.

$$\tag{PhD thesis}\label{Thesis}$$

PhD thesis

• N. Mohammadi, 3D high-resolution imaging of lithospheric VP, VS, and density structure in the Alps using full-waveform inversion of the teleseismic P waves, ongoing (defense scheduled end of 2024).

$$\tag{Technical reports}\label{Technical reports}$$

Technical Reports

$$\tag{Proposals}\label{Proposals}$$

Proposal ANR AAPG2020

1. WIND team, Probing the 3D Alpine Lithosphere by Full Waveform Inversion of the AlpArray teleseismic data, preproposal ANR AAPG 2020, 4 pages, 2020 (pdf).
2. WIND team, Probing the 3D Alpine Lithosphere by Full Waveform Inversion of the AlpArray teleseismic data, finalproposal ANR AAPG 2020, 20 pages, 2020 (pdf).

$$\tag{Activity reports}\label{Activity reports}$$

Activity reports

1. Activity report 18 months - 15 July 2022 (pdf, 95Mb) (compressed pdf, 4.2Mb).