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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Insights from the Mw 7.8 2012 Haida Gwaii Earthquake: Static Stress Modelling and Empirical Green's Function Analysis

Hobbs, Tiegan Elizabeth 06 August 2014 (has links)
This thesis presents the results of three independent but related studies of aspects of the Mw 7.8 2012 Haida Gwaii earthquake, which was the second largest Canadian earthquake in recorded history. This event ruptured an area of roughly 150 by 40 km on a gently northeast-dipping thrust fault off the west coast of Moresby Island, British Columbia. This event was felt over 1600 km away from the epicentre, and produced tens of thousands of aftershocks. Adjacent to the mainshock fault plane is the Queen Charlotte Fault, the site of the largest event recorded in Canada: the 1949 Ms 8.1 strike-slip earthquake whose rupture extended as far south as this 2012 event and roughly as far north as an Mw 7.5 strike slip event which occurred on 5 January 2013. The 2012 thrust event was a surprise to some members of the seismological community as it ruptured a slab offshore of a major strike slip boundary. This earthquake therefore presents an excellent opportunity to constrain the tectonics and seismic hazard off the northwest coast of British Columbia. Herein a Coulomb stress transfer analysis is performed using finite fault models which incorporate both seismological and geodetic data. Static stress changes are projected onto optimally-oriented fault planes, determined using regional tectonic stresses in addition to mainshock stress; nodal planes, determined by aftershock centroid moment tensors; and onto the Queen Charlotte Fault. I find that aftershocks are generally consistent with Coulomb stress changes using optimal planes and known nodal planes, although the latter have slightly higher percentages of events consistent with triggering. I find that the Queen Charlotte Fault experienced stress changes greater than the empirically-determined threshold for triggering. This is particularly important as the southern extent of this fault is believed to lie in a seismic gap going back at least 116 years. With added stress from the mainshock and a lack of post-mainshock seismicity occurring in this seismic gap, it is a likely location for future earthquakes on this portion of the plate boundary. To obtain estimates of rupture parameters, an empirical Green's function technique and directivity analysis is performed. This method constrains rupture kinematics of the mainshock using systematic azimuthal variations in relative source time functions. My results indicate a rupture that progressed mainly to the northwest and updip. Subevent analysis confirms the existence of at least two subevents, with the first being roughly twice as large as the second. The results herein are similar to those found using finite fault inversion, but are better able to explain observed surface wave amplification at Alaskan seismic stations. My findings help support the idea that strong surface wave shaking may have resulted in delayed-onset dynamic triggering of the 2013 Craig event, through an unknown but intermediate mechanism that accounts for the two-month hiatus. Finally, an attempt was made to relocate all offshore aftershocks for this sequence by improving locations for events during a two-week ocean bottom seismometer deployment. This dataset includes a wider range of source-station azimuths and decreases the minimum source-receiver distance, relative to locations that only use land stations. My locations therefore represent the best-constrained depths for M greater than or equal to 3 offshore aftershocks occurring during the two-week deployment, and help constrain reasonable depth estimates from other relocation techniques. For events located using only ocean bottom seismometers I determine the time residual between observed and predicted phase arrivals at land stations to be used as a correction for all aftershocks recorded at land stations through the entire aftershock sequence. Although I was not able to find consistent time residuals I present suggestions for future implementations of this technique to this dataset, and discuss challenges associated with location of offshore earthquakes in regions with sparse regional seismic networks. All of these findings contribute to a more thorough understanding of this 2012 earthquake, as well as the tectonics of southern Haida Gwaii. I pay particular attention to identification of hazard within a seismic gap south of Moresby Island, and the northwest rupture directivity of the 2012 mainshock. / Graduate / 0373 / tiegan.hobbs@gmail.com
42

Evolution morphostructurale des bassins de marge active en subduction : l'exemple du bassin avant arc de Hawke Bay en Nouvelle-Zélande = Morphostructural evolution of active subduction margin basins : the example of the Hawke Bay forearc basin, New Zealand /

Paquet, Fabien. January 2008 (has links)
Thesis (Ph. D.) -- l'Université de Rennes, 2007. / "Thése de Doctorat de l'Université de Rennes 1 réalisée en co-tutelle avec l'Université de Canterbury (Christchurch, Nouvelle-Zélande)." "Soutenue le 9 novembre 2007." Includes bibliographical references. Also available via WWW.
43

Morphostructural evolution of active margin basins : the example of the Hawke Bay forearc basin, New Zealand : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Geology at the University of Canterbury /

Paquet, Fabien. January 2007 (has links)
Thesis (Ph. D.)--University of Canterbury, 2007. / Typescript (photocopy). "Ph.D. thesis realized in cotutelle with the University of Rennes 1, Rennes, France." Includes bibliographical references. Also available via the World Wide Web.
44

Late holocene coseismic subsidence and coincident tsunamis, southern Cascadia subduction zone, Hookton Slough, WIGI (Humboldt Bay), California /

Patton, Jason Robert. January 2004 (has links) (PDF)
Thesis (M.S.)--Humboldt State University, 2004. / Includes bibliographical references (leaves 59-65). Also available via the Internet.
45

Crustal and upper mantle structure for the Pacific Northwest from an analysis of short-period teleseismic network data /

Dewberry, Shawn Robert. January 1996 (has links)
Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [137]-146).
46

Géoide altimétrique et lithosphère océanique application a l'identification de nouvelles structures intraplaques /

Baudry, Nicolas. January 1900 (has links)
Thesis (Ph. D.)--Université de Paris-Sud, 1987. / "Thèse présentée pour obtenir le titre de Docteur en Sciences ... soutenue le 22 octubre 1987." At head of title: Sujet. Includes bibliographical references.
47

The velocity field in the northeast Atlantic from satellite- tracked drifting buoys

Giannetti, Paolo. January 1900 (has links)
Thesis (M.S.)--Naval Postgraduate School, 1993. / "September 1993." Includes bibliographical references (p. 70-72).
48

Juan de Fuca subducting plate geometry and intraslab seismicity /

Medema, Guy Frederick. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 74-82).
49

Schistes bleus et déformation progressive : l'exemple de l'île de Groix, Massif armoricain.

Quinquis, Hervé, January 1900 (has links)
Th. 3e cycle--Sci. de la terre--Rennes 1, 1980. N°: 601.
50

The effect of water on mantle melting

Hall, Leonie January 1999 (has links)
No description available.

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