Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding
Presented in this thesis are some basic concepts and applications of seismic hazard analysis and the elements that influence the amplitude and geometric attenuation of earthquake ground motion. This thesis centers on the identification of the styles of failure, focal mechanisms, and the state of reg...
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Uppsala universitet, Geofysik
2006
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ftuppsalauniv:oai:DiVA.org:uu-7292 2023-05-15T16:52:22+02:00 Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding Hagos, Lijam Zemichael 2006 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7292 eng eng Uppsala universitet, Geofysik Uppsala : Acta Universitatis Upsaliensis Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 242 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7292 urn:isbn:91-554-6721-0 info:eu-repo/semantics/openAccess Earth sciences Seismic hazard Focal mechanism Moment tensor inversion Stress field Afar depression Eritrea Geovetenskap Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2006 ftuppsalauniv 2023-02-23T21:44:12Z Presented in this thesis are some basic concepts and applications of seismic hazard analysis and the elements that influence the amplitude and geometric attenuation of earthquake ground motion. This thesis centers on the identification of the styles of failure, focal mechanisms, and the state of regional stress in the study area. Seismic hazard is a complex problem often involving considerable uncertainties. Therefore it is reasonable to consider different seismic hazard analysis approaches in order to as robustly as possible define zones of different levels of hazard. With the aim of characterizing and quantifying hazard in the east African region of Eritrea and its surroundings, a study is included in the thesis presenting hazard maps constructed using two non-parametric probabilistic seismic hazard analysis (PSHA) approaches. Peak ground acceleration (PGA) values for 10% probability of exceedence in 50 years are computed at given grid points for the whole selected area and results from both methods are compared. Other aspects addressed in the thesis include the determination of source parameters of selected earthquakes that occur in the Afar region. The styles of faulting, the mechanisms involved during the rupture process and the states of stress along the major tectonic features are also highlighted. Source parameters for selected events in the region were re-evaluated and improved solutions obtained. An aftershock sequence in the Hengill volcanic area in SW Iceland, following the major event that occurred on June 4, 1998, was used to investigate improved methodologies for moment tensor using a relative approach. The sensitive and spatially dense seismic network in this area reveals large sets of clustered events allowing the power of the new methodology to be demonstrated and providing greater insight into the tectonic implications of the activity in the area. Doctoral or Postdoctoral Thesis Iceland Uppsala University: Publications (DiVA) Hengill ENVELOPE(-21.306,-21.306,64.078,64.078) |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Earth sciences Seismic hazard Focal mechanism Moment tensor inversion Stress field Afar depression Eritrea Geovetenskap |
spellingShingle |
Earth sciences Seismic hazard Focal mechanism Moment tensor inversion Stress field Afar depression Eritrea Geovetenskap Hagos, Lijam Zemichael Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding |
topic_facet |
Earth sciences Seismic hazard Focal mechanism Moment tensor inversion Stress field Afar depression Eritrea Geovetenskap |
description |
Presented in this thesis are some basic concepts and applications of seismic hazard analysis and the elements that influence the amplitude and geometric attenuation of earthquake ground motion. This thesis centers on the identification of the styles of failure, focal mechanisms, and the state of regional stress in the study area. Seismic hazard is a complex problem often involving considerable uncertainties. Therefore it is reasonable to consider different seismic hazard analysis approaches in order to as robustly as possible define zones of different levels of hazard. With the aim of characterizing and quantifying hazard in the east African region of Eritrea and its surroundings, a study is included in the thesis presenting hazard maps constructed using two non-parametric probabilistic seismic hazard analysis (PSHA) approaches. Peak ground acceleration (PGA) values for 10% probability of exceedence in 50 years are computed at given grid points for the whole selected area and results from both methods are compared. Other aspects addressed in the thesis include the determination of source parameters of selected earthquakes that occur in the Afar region. The styles of faulting, the mechanisms involved during the rupture process and the states of stress along the major tectonic features are also highlighted. Source parameters for selected events in the region were re-evaluated and improved solutions obtained. An aftershock sequence in the Hengill volcanic area in SW Iceland, following the major event that occurred on June 4, 1998, was used to investigate improved methodologies for moment tensor using a relative approach. The sensitive and spatially dense seismic network in this area reveals large sets of clustered events allowing the power of the new methodology to be demonstrated and providing greater insight into the tectonic implications of the activity in the area. |
format |
Doctoral or Postdoctoral Thesis |
author |
Hagos, Lijam Zemichael |
author_facet |
Hagos, Lijam Zemichael |
author_sort |
Hagos, Lijam Zemichael |
title |
Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding |
title_short |
Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding |
title_full |
Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding |
title_fullStr |
Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding |
title_full_unstemmed |
Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding |
title_sort |
earthquake sources, the stress field and seismic hazard : a study in eritrea and its surrounding |
publisher |
Uppsala universitet, Geofysik |
publishDate |
2006 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7292 |
long_lat |
ENVELOPE(-21.306,-21.306,64.078,64.078) |
geographic |
Hengill |
geographic_facet |
Hengill |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 242 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7292 urn:isbn:91-554-6721-0 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766042554687553536 |