Acoustic full-waveform to elastic pre-stack seismic inversion of the Yakutat Terrane, Gulf of Alaska

dc.contributor.advisorSen, Mrinal K.
dc.creatorAlqatari, Hala
dc.creator.orcid0000-0003-1941-7036
dc.date.accessioned2018-09-14T21:26:35Z
dc.date.available2018-09-14T21:26:35Z
dc.date.created2018-08
dc.date.issued2018-08-16
dc.date.submittedAugust 2018
dc.date.updated2018-09-14T21:26:36Z
dc.description.abstractThe Yakutat-North American collision in the Gulf of Alaska has developed a complex subduction zone followed by major deformations such as the Chugach-St Elias mountain range creation, intensified exhumation, fold and thrust-fault formation. I generate a compressional velocity model of the Yakutat microplate using two-dimensional acoustic and isotropic time-domain full waveform inversion (FWI) of marine seismic reflection and refraction data from the STEEP project (ST. Elias Erosion/tectonics Project). FWI is a non-linear data-fitting algorithm that aims to recover subsurface parameters from the recorded seismic wavefield. Seismic wave propagation along the Yakutat terrane is simulated using a staggered-grid finite difference modeling scheme. Drawbacks associated with FWI is cycle skipping during the minimization process, which results in converging to the wrong velocity model. Starting with a good initial model that contains the low-frequency information can help mitigate this issue. The starting velocity model input to FWI in this case is generated by a traveltime tomographic inversion of ocean-bottom seismometer and streamer seismic data. Data preconditioning includes muting, filtering, noise removal and amplitude rescaling of the field seismic data to match the corresponding amplitudes of the synthetic traces. The forward model is able to produce a good match between the observed and the modeled wavefield within half the propagated wavelength. I use the FWI result, which shows good correlation with the industry well, as an input to two additional seismic inversion methods: acoustic post-stack and elastic pre-stack seismic inversion in order to recover shear impedance and density models along the seismic line. Extending the problem to the elastic medium is important to support more advanced seismic interpretation. Both techniques were able to produce higher-resolution images of the Yakutat terrane that are well correlated with the well response. Structural complexities identified in the generated models include the northwest-dipping Pamplona fault system, the offshore folding zone, thickening of the Yakutat basement and, lastly, significantly lower velocities in the Poul Creek formation compared to the younger Yakataga formation, which may be attributed to high-fluid pressure within that formation.
dc.description.departmentEarth and Planetary Sciences
dc.format.mimetypeapplication/pdf
dc.identifierdoi:10.15781/T2TQ5RZ9N
dc.identifier.urihttp://hdl.handle.net/2152/68455
dc.language.isoen
dc.subjectFull-waveform
dc.subjectInversion
dc.titleAcoustic full-waveform to elastic pre-stack seismic inversion of the Yakutat Terrane, Gulf of Alaska
dc.typeThesis
dc.type.materialtext
thesis.degree.departmentGeological Sciences
thesis.degree.disciplineGeological Sciences
thesis.degree.grantorThe University of Texas at Austin
thesis.degree.levelMasters
thesis.degree.nameMaster of Science in Geological Sciences

Access full-text files

Original bundle

Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
ALQATARI-THESIS-2018.pdf
Size:
16.76 MB
Format:
Adobe Portable Document Format

License bundle

Now showing 1 - 1 of 1
No Thumbnail Available
Name:
LICENSE.txt
Size:
1.84 KB
Format:
Plain Text
Description: