Andreuttiova, Lucia;
(2023)
Quantitative Assessment of Three-Dimensional Surface Displacement Caused by Large-magnitude Normal Earthquakes from Optical Image Correlation of Historical Aerial Photographs.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The measurements that characterise normal earthquakes almost exclusively report the offset recorded on the fault scarp. However, the absence of data away from the main fault means that the total displacement caused by the extensional dip-slip faulting still remains poorly characterised. As continental normal earthquakes are a source of a significant seismic hazard, it is necessary to improve our understanding of these ruptures in order to develop better mitigation and hazard forecast strategies. In this work, we use optical image correlation to detect the three-dimensional displacement created during large continental normal earthquakes. Optical image correlation (OIC) has previously been successfully used to detect movement created during recent strike-slip events. We extend the application of OIC to normal earthquakes and adapt the processing chain to historical imagery. These modifications allow us to detect a three-dimensional displacement along normal faults. The focus of this study is the three large-magnitude normal events from Basin and Range Province: the 1954 Dixie Valley - Fairview Peak earthquake sequence, the 1959 Hebgen Lake earthquake, and the 1983 Borah Peak earthquake. We utilise the results of optical image correlation (OIC) to calculate the on- and off-fault displacement surrounding these normal faults. A comparison between OIC and field data reveals significant along-strike variations. The excess slip observed in the OIC data indicates distributed off-fault deformation, while the higher displacement measured in the field may be attributed to changes in fault geometry. These findings illustrate that normal faults exhibit complex geometries, emphasising the need for further investigation to fully comprehend their properties. This study significantly enhances our understanding of the behaviour and subsurface structure of normal faults. Furthermore, it pioneers advancements in the methodology for stereo-reconstruction from historical data.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Quantitative Assessment of Three-Dimensional Surface Displacement Caused by Large-magnitude Normal Earthquakes from Optical Image Correlation of Historical Aerial Photographs |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10178617 |
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