Analysis of artifacts in local tomography with nonsmooth attenuation

Author(s):  
Alexander Katsevich
Keyword(s):  
2011 ◽  
Vol 4 (1) ◽  
pp. 200-219 ◽  
Author(s):  
A. Katsevich ◽  
M. Silver ◽  
A. Zamyatin

Author(s):  
A.G. Ramm ◽  
A.I. Katsevich
Keyword(s):  

2015 ◽  
Vol 58 (2) ◽  
Author(s):  
Manuela Volpe ◽  
Simone Atzori ◽  
Antonio Piersanti ◽  
Daniele Melini

<p>We present a Finite Element inverse analysis of the static deformation field for the M<sub>w</sub>= 6.3, 2009 L’Aquila earthquake, in order to infer the rupture slip distribution on the fault plane. An univocal solution for the rupture slip distribution has not been reached yet with negative impact for reliable hazard scenarios in a densely populated area. In this study, Finite Element computed Green’s functions were implemented in a linear joint inversion scheme of geodetic (GPS and InSAR) and seismological (strong motion) coseismic deformation data. In order to fully exploit the informative power of our dense dataset and to honor the complexities of the real Earth, we implemented an optimized source model, represented by a fault plane subdivided in variable size patches, embedded in a high-resolution realistic three-dimensional model of the Apenninic seismo-tectonic setting, accounting for topographic reliefs and rheological heterogeneities deduced from local tomography. We infer that the investigated inversion domain contains two minima configurations in the solution space, i.e. a single- and a double-patch slip distribution, which are almost equivalent, so that the available datasets and numerical models are not able to univocally discriminate between them. Nevertheless our findings suggest that a two high-slip patch pattern is slightly favoured.</p>


Author(s):  
Xiaoxia Yin ◽  
Brian W.-H. Ng ◽  
Bradley Ferguson ◽  
Derek Abbott

1992 ◽  
Vol 52 (4) ◽  
pp. 1193-1198 ◽  
Author(s):  
Adel Faridani ◽  
Erik L. Ritman ◽  
Kennan T. Smith
Keyword(s):  

Author(s):  
Xiaoxia Yin ◽  
Brian W.-H. Ng ◽  
Derek Abbott
Keyword(s):  

2013 ◽  
Vol 21 (1) ◽  
pp. 242-250 ◽  
Author(s):  
Elisabeth Schültke ◽  
Ralf Menk ◽  
Bernd Pinzer ◽  
Alberto Astolfo ◽  
Marco Stampanoni ◽  
...  

Gold nanoparticles are excellent intracellular markers in X-ray imaging. Having shown previously the suitability of gold nanoparticles to detect small groups of cells with the synchrotron-based computed tomography (CT) technique bothex vivoandin vivo, it is now demonstrated that even single-cell resolution can be obtained in the brain at leastex vivo. Working in a small animal model of malignant brain tumour, the image quality obtained with different imaging modalities was compared. To generate the brain tumour, 1 × 105C6 glioma cells were loaded with gold nanoparticles and implanted in the right cerebral hemisphere of an adult rat. Raw data were acquired with absorption X-ray CT followed by a local tomography technique based on synchrotron X-ray absorption yielding single-cell resolution. The reconstructed synchrotron X-ray images were compared with images obtained by small animal magnetic resonance imaging. The presence of gold nanoparticles in the tumour tissue was verified in histological sections.


2020 ◽  
Vol 57 (5) ◽  
pp. 601-616
Author(s):  
Jamshed Aminov ◽  
Ivan Koulakov ◽  
Andrey Jakovlev ◽  
Junmeng Zhao ◽  
Sami El-Khrepy ◽  
...  

The Pamir and Hindu Kush are examples of a puzzling collision system where a complex junction of colliding lithospheric plates coexists with intermediate depth seismicity at 300 km. In this study, we constructed a new tomography model using travel time data from local events recorded by the TIPAGE (Tien Shan – Pamir Geodynamic program) network. In addition to the P- and S-wave velocities down to 200 km, we derived the azimuthal anisotropy. The velocity anomalies were consistent with the results of previous studies. In the crust, the velocity structure and anisotropy directions were mainly oriented along major suture zones. At depths of 80–120 km, a narrow low-velocity anomaly coinciding with the distribution of deep seismicity was interpreted as a trace of entrained crustal material by the dipping lithosphere. The anisotropy directions at these depths were mainly oriented northwest–southeast and were interpreted as indicating the direction of the motion of colliding plates. The difference in the magnitude of anisotropy south and north of the Pamir seismic zone suggests that the lithosphere coming from the south possesses less anisotropy than that of the Asian plate. The local tomography model was supplemented by previously computed regional tomography that expanded the area both laterally and axially. Beneath the Pamir, both continental plates coming from the north and south form a drop-shaped anomaly that will possibly delaminate in time. Beneath the Hindu Kush, we could clearly trace a continuous almost vertical subduction of the Katawaz block from the south. Thus, the continental collision beneath the Pamir and subduction beneath the Hindu Kush are separate processes with different rates and directions of plate movement.


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