SEMINAR: Jan Norbisrath, MGG Student Seminar, TODAY @ 12 PM

[Kelly Jackson <kjackson@rsmas.miami.edu>]

MGG STUDENT SEMINAR 

presents

JAN NORBISRATH

Sub-micron Digital Image Analysis (BIBSEM-DIA), Pore Geometries and Electrical Resistivity in Carbonate Rocks

Tuesday, March 19, 2013

12:00 PM 

CIMAS Conference Room

Abstract:  Traditional ambient noise tomography methods using regular grid nodes are usually ill posed because the inversion grids do not always represent the distribution of ray paths. In addition, large grid spacing is generally used to reduce the number of inversion parameters, which may not be able to solve for small-scale velocity structure. Adaptive tomography method with irregular grids provides a few advantages over the traditional methods. Firstly, irregular grids with different sizes and shapes can fit the ray distribution better and the traditionally ill-posed problem can become more stable due to the different parameterizing methods. Secondly, the data in the area with dense ray sampling will be sufficiently utilized so that model resolution can be greatly improved. Both synthetic and real data are used to test the newly developed tomography algorithm. In synthetic data tests, we compare resolution and stability of traditional and adaptive methods. The results show that adaptive tomography is more stable and performs better in improving the resolution in the area with dense ray sampling. For real data, we extract the ambient noise signals in the seismic data obtained from the Southern California Earthquake Data Center, recorded by 14 broadband stations. The group velocity results of Rayleigh wave well recover the local structures. High velocity anomalies are shown in cold southern Sierra Nevada crust, Tehachapi Mountains and west San Gabriel Mountains. In contrast to these high anomalies, southern San Joaquin Valley and western Mojave are dominated by low velocity bodies.