Two-station Rayleigh wave tomography of Canada

Simple item page
dc.contributor.authorSharma, Aarti
dc.contributor.examiningcommitteeFerguson, Ian (Earth Sciences)en_US
dc.contributor.examiningcommitteeCamacho, Alfredo (Earth Sciences)en_US
dc.contributor.supervisorFrederiksen, Andrew
dc.contributor.supervisorDarbyshire, Fiona
dc.date.accessioned2023-01-18T15:25:09Z
dc.date.available2023-01-18T15:25:09Z
dc.date.copyright2023-01-02
dc.date.issued2022-11-21
dc.date.submitted2023-01-03T01:04:08Zen_US
dc.degree.disciplineEarth Sciencesen_US
dc.degree.levelMaster of Science (M.Sc.)en_US
dc.description.abstractSeismic tomography is a common method used to study the lithosphere and can reveal evidence of past and present tectonic and geodynamic processes. In largely aseismic areas such as central and eastern Canada, single-station measurements of surface-wave dispersion will provide limited and uneven resolution; two-station measurements allow the use of a larger selection of earthquakes (i.e., extending to teleseismic events) while still preserving a regional-scale measurement. This work examines seismic velocity and anisotropy variations of the Canadian lithosphere using two-station-based surface-wave tomography, to obtain new insights into the formation history of the continent. A cross-correlation method was used to obtain new two-station dispersion curves (a total of 117) which were added to a dataset of previously published measurements. These were chosen to fill in gaps in ray coverage and to maximize azimuthal distribution, particularly across the Prairies and the Cordillera. Tomographic inversion was used to calculate anisotropic phase velocity maps for periods of 15-400 s, following outlier exclusion and resolution testing. The phase velocity maps show that the low velocity Cordilleran lithosphere contains two southern zones (west and east) with different anisotropy, which are interpreted to be due to the influence of the subducting Juan de Fuca plate in the west. A sharp Cordillera-craton boundary with the Canadian Shield is also noted, which shifts eastward near the US border. A very low velocity anomaly is observed beneath southeastern Saskatchewan which is likely linked to a mantle suture in this area. The highest velocities are seen beneath the craton, with particularly high velocities in Nunavut (northern Canada) and the western Superior Province. Strong E-W anisotropy is observed beneath the western Superior resulting from frozen lithospheric fabric. A clear distinction between the Precambrian Shield and the lower velocity Appalachian domains is also noted. This Appalachian low velocity zone is thought to be associated with the present-day Northern Appalachian Anomaly, rather than the Great Meteor Hotspot track.en_US
dc.description.noteFebruary 2023en_US
dc.description.sponsorshipNSERCen_US
dc.identifier.urihttp://hdl.handle.net/1993/37145
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectCanadaen_US
dc.subjectSeismic anisotropyen_US
dc.subjectPhase velocityen_US
dc.subjectRayleigh wave tomographyen_US
dc.titleTwo-station Rayleigh wave tomography of Canadaen_US
dc.typemaster thesisen_US
local.subject.manitobanoen_US
project.funder.identifierhttps://doi.org/10.13039/100010318en_US
project.funder.nameUniversity of Manitobaen_US
Files
Original bundle
Now showing 1 - 2 of 2
Thumbnail Image
Name:
Sharma_Aarti.pdf
Size:
44.81 MB
Format:
Adobe Portable Document Format
Description:
Thesis
Download
Thumbnail Image
Name:
all_curves.zip
Size:
4.26 MB
Format:
Winzipped zip file
Description:
Dispersion curve data
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
2.2 KB
Format:
Item-specific license agreed to upon submission
Description:
Download
Collections
FGS - Electronic Theses and Practica