SIILEG · 3D modelling with sequential integrated inversion of Pand S Travel Times from local earthquakes and gravity data: the crustal structure of the Eastern Carpathians in Romania
6РП — Действия „Мария Кюри“
- Период
- 2005-02-01 → 2007-01-31
- Финансиране от ЕС
- 149 670 €
- Участници
- 1
- Схема
- EIF
Линиите свързват координатора с партньорите.
Накратко на български
Структурата на земната кора в района на Вранча в Румъния се анализира чрез 3D модели на сеизмични вълни и плътност. Това помага за по-точното определяне на свойствата на материалите в земната кора и намалява грешките при тълкуването им.
Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.
Резултати накратко
Final Activity Report Summary - SIILEG (3D Modelling ... of Pand S Travel Times from local Earthquakes and gravity data: the crustal structure of the Eastern Carpathians in Romania)
Within this project, three-dimensional velocities of primary (P-wave) and secondary waves (S-waves), i.e. Vp, Vs, Vp/Vs and density parameters characterising the Vrancea seismogenic Zone were defined for a 200 km thick volume covering an area of 230 times 230 km. With our results: 1. we overcame two major limitations of the previous work, namely the lack of a high resolution three-dimensional S-wave and density model down to 200 km; and 2. we demonstrated the diagnostic power of a combined interpretation of three-dimensional Vp, Vs, Vp/Vs and density earth models. For our goal, we successfully applied the tomographic inversion method of sequential integrated inversion proposed by Tondi and de Franco (2006) to shot data collected during the Vranchea99 (Hauser et al., 2001) and Vranchea2001 (Landes et al., 2004) seismic refraction experiments to local earthquake data collected during the Calixto (EOS, 1998) experiment and to recent gravity measurements of the studied area (Besutiu et al., 2004). We viewed the measured data as a realisation of a stochastic process generated by the physical parameters to be sought and the solution was found through the minimisation of a probability density function which included the information from gravity measurements, the information from picked travel times and the information on the physical correlation among density and P-wave or S-wave velocity. The reliability of the reconstructed models, which explained equally well both travel times and gravity data, was quantified through a restoring test and the estimation of travel times and gravity residuals. The analysis of the results, while putting constraints on the material properties within the slab structure allowed us to reduce ambiguity of the interpretation of the nature of the convergence process. Hence: 1. we substantiated the subduction model and eliminated the continental lithospheric delamination model; 2. we associated intermediate depth seismicity of the eastern Carpathians to the observed sharp lateral Vp/Vs variations presumably generated by contact between the dense and cold slab and the lithospheric mantle in the shallower part or the asthenosphere in the deeper part. This contrast was particularly evident between 100 and 150 km of depth, where the maximum historical and analysed seismic energy release was concentrated.
Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз
Цел на проекта
In order to properly localise earthquakes and define, especially in tectonically active areas, the seismic risk, there is the necessity to have reliable earth models. For the time being, seismic risk tables are still evaluated with the use of very simple 1 D models and so their reliability is questionable. This project wants to bring some useful novelty in the field.The project is placed in the framework of the joint inversion of different geophysical information; in particular it considers the coupling between the seismological data coming from local earthquakes and the gravity signal. We want to develop a set of programs to operate with 3-D volumes, which will allow the accurate reconstruction of 3-D velocity and density earth structures starting from P-wav e and S-wave local earthquake events and gravity measurements.The completion of the research project includes:a) the development of software to interface a complete ray tracing program (CRT, developed by the Geophysical group in Prague) to the NonLinLoc location program developed by Anthony Lomax of the Geosciènce Azur in France;b) the extension of the algorithm for Sequential Integrated Inversion of seismic and gravity data, developed by the applicant, to the analysis of P and S-wave travel times from local earthquakes;c) tests of the proposed methodology with synthetic data;d) the analysis of local seismological events recorded as part of the European project VRANCEA99 (a multi-disclipinary project to study the Eastern Carpathians in Romania) and to a collection of gravity measurements produced by the Geophysical Institute in Bucharest for the area.The relocation of local events and the recovery of detailed Vp, Vs and density models will give insights on the upper limit of the sub-ducting slab of oceanic lithosphere. Further, the model parameters images can be a valuable tool for the hazard assessment of the region. A densely populated town, Bucharest, lies nearby and needs attention.
Оригинален текст от CORDIS (на английски).
Участници
- UNIVERSITE LOUIS PASTEUR, STRASBOURG 1 · STRASBOURGКоординаторФранция
Връзки
Данни: CORDIS, © Европейски съюз