Complex Rupture Processes Of Large Strike-Slip Earthquakes And Receiver Function Analysis Of Crust And Upper Mantle In Active Tectonic Settings

Persistent Link:
http://hdl.handle.net/10150/194258
Title:
Complex Rupture Processes Of Large Strike-Slip Earthquakes And Receiver Function Analysis Of Crust And Upper Mantle In Active Tectonic Settings
Author:
Ozacar, Atilla Arda
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This dissertation explores the uses for data collected at broadband seismic stations to investigate source process of large strike-slip earthquakes and crust and upper mantle structure within active continental tectonic settings. First, we analyzed rupture mechanism of the 2002 Denali earthquake (M = 7.9) and the 2001 Kunlun earthquake (M = 7.8) using teleseismic P waveforms. According to our results, the Denali earthquake began with initial thrusting and later ruptured a 300-km-long segment with a right-lateral strike-slip mechanism. In contrast, the Kunlun earthquake nucleated along an extensional step-over with a complex mechanism and later ruptured a 350-km-long segment with a left-lateral mechanism. Both earthquakes have source properties similar to interplate earthquakes and display strong directivity and slip heterogeneity suggesting that the middle fault segments are weaker.Next, we applied receiver function techniques to image the crust and upper mantle beneath active tectonic regions. In central Tibet, we found strong seismic anisotropy that changes with depth. Especially, mid-crustal anisotropy is consistent with a near-horizontal rock fabric induced by crustal flow. Near the San Andreas Fault in Parkfield, crust is relatively thin (26 km) and characterized by high Vp/Vs (1.88). At the base of the crust, receiver functions indicate strong anisotropy in a low velocity, high Vp/Vs, serpentinite layer that is most likely a fossilized fabric of Farallon plate subduction. Beneath the East Anatolian Plateau, our analysis reveals a thin crust (<45 >km) consistent with the high plateau supported by hot partially molten asthenosphere near the crust. Vp/Vs values are low at the Bitlis suture and high within the plateau due to partial melting. Seismic imaging of 410 and 660 km discontinuities also reveals anticorrelated topography and distinct zones of diminished amplitude associated with detached slabs and delaminated fragments of lithospheric mantle. In the south, slab becomes deeper and horizontally deflected towards east suggesting westward migration of slab detachment and resistance to slab penetration at 660 km discontinuity. At the center of the study area, the transition zone is thin (230 km) and indicates the presence of warm mantle within the transition zone beneath the plateau.
Type:
text; Electronic Dissertation
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Beck, Susan L.
Committee Chair:
Beck, Susan L.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleComplex Rupture Processes Of Large Strike-Slip Earthquakes And Receiver Function Analysis Of Crust And Upper Mantle In Active Tectonic Settingsen_US
dc.creatorOzacar, Atilla Ardaen_US
dc.contributor.authorOzacar, Atilla Ardaen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis dissertation explores the uses for data collected at broadband seismic stations to investigate source process of large strike-slip earthquakes and crust and upper mantle structure within active continental tectonic settings. First, we analyzed rupture mechanism of the 2002 Denali earthquake (M = 7.9) and the 2001 Kunlun earthquake (M = 7.8) using teleseismic P waveforms. According to our results, the Denali earthquake began with initial thrusting and later ruptured a 300-km-long segment with a right-lateral strike-slip mechanism. In contrast, the Kunlun earthquake nucleated along an extensional step-over with a complex mechanism and later ruptured a 350-km-long segment with a left-lateral mechanism. Both earthquakes have source properties similar to interplate earthquakes and display strong directivity and slip heterogeneity suggesting that the middle fault segments are weaker.Next, we applied receiver function techniques to image the crust and upper mantle beneath active tectonic regions. In central Tibet, we found strong seismic anisotropy that changes with depth. Especially, mid-crustal anisotropy is consistent with a near-horizontal rock fabric induced by crustal flow. Near the San Andreas Fault in Parkfield, crust is relatively thin (26 km) and characterized by high Vp/Vs (1.88). At the base of the crust, receiver functions indicate strong anisotropy in a low velocity, high Vp/Vs, serpentinite layer that is most likely a fossilized fabric of Farallon plate subduction. Beneath the East Anatolian Plateau, our analysis reveals a thin crust (<45 >km) consistent with the high plateau supported by hot partially molten asthenosphere near the crust. Vp/Vs values are low at the Bitlis suture and high within the plateau due to partial melting. Seismic imaging of 410 and 660 km discontinuities also reveals anticorrelated topography and distinct zones of diminished amplitude associated with detached slabs and delaminated fragments of lithospheric mantle. In the south, slab becomes deeper and horizontally deflected towards east suggesting westward migration of slab detachment and resistance to slab penetration at 660 km discontinuity. At the center of the study area, the transition zone is thin (230 km) and indicates the presence of warm mantle within the transition zone beneath the plateau.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBeck, Susan L.en_US
dc.contributor.chairBeck, Susan L.en_US
dc.contributor.committeememberZandt, Georgeen_US
dc.contributor.committeememberBennett, Richard A.en_US
dc.contributor.committeememberChase, Clement G.en_US
dc.identifier.proquest2221en_US
dc.identifier.oclc659747390en_US
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