Joint seismic and gravity data inversion to image intra-crustal structures: The Ivrea Geophysical Body along the Val Sesia Profile (Piedmont, Italy)

0544667 - GFÚ 2022 RIV CH eng J - Journal Article
Scarponi, M. - Hetényi, G. - Plomerová, Jaroslava - Solarino, S. - Baron, L. - Petri, B.
Joint seismic and gravity data inversion to image intra-crustal structures: The Ivrea Geophysical Body along the Val Sesia Profile (Piedmont, Italy).
Frontiers in Earth Science. Roč. 9, May (2021), č. článku 671412. E-ISSN 2296-6463
R&D Projects: GA MŠMT(CZ) LM2015079; GA ČR(CZ) GA21-25710S
Institutional support: RVO:67985530
Keywords : joint inversion * seismic receiver functions * gravity anomalies * Ivrea Geophysical Body * Ivrea-Verbano Zone * continental crust * intra-crustal structure
OECD category: Volcanology
Impact factor: 3.661, year: 2021
Method of publishing: Open access
https://www.frontiersin.org/articles/10.3389/feart.2021.671412/full

We present results from a joint inversion of new seismic and recently compiled gravity data to constrain the structure of a prominent geophysical anomaly in the European Alps: the Ivrea Geophysical Body (IGB). We investigate the IGB structure along the West-East oriented Val Sesia profile at higher resolution than previous studies. We deployed 10 broadband seismic stations at 5 km spacing for 27 months, producing a new database of similar to 1000 high-quality seismic receiver functions (RFs). The compiled gravity data yields 1 gravity point every 1-2 km along the profile. We set up an inversion scheme, in which RFs and gravity anomalies jointly constrain the shape and the physical properties of the IGB. We model the IGB's top surface as a single density and shear-wave velocity discontinuity, whose geometry is defined by four, spatially variable nodes between far-field constraints. An iterative algorithm was implemented to efficiently explore the model space, directing the search toward better fitting areas. For each new candidate model, we use the velocity-model structures for both ray-tracing and observed-RFs migration, and for computation and migration of synthetic RFs: the two migrated images are then compared via cross-correlation. Similarly, forward gravity modeling for a 2D density distribution is implemented. The joint inversion performance is the product of the seismic and gravity misfits. The inversion results show the IGB protruding at shallow depths with a horizontal width of similar to 30 km in the western part of the profile. Its shallowest segment reaches either 3-7 or 1-3 km depth below sea-level.
Permanent Link: http://hdl.handle.net/11104/0321504