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Seismic Receiver and Noise Correlation Based Studies in AustraliaSaygin, Erdinc, erdinc.saygin@anu.edu.au January 2007 (has links)
This thesis is directed at exploiting information in the coda of
seismic phases and the ambient noise field to provide new constraints
on the structure of the Australian Continent.
¶
The exploitation of the immediate coda following the onset of P waves from
a distant earthquake using radial receiver functions is now a well
established method. The 40 sec interval following P contains
reverberations and conversions, by deconvolving the radial component
trace with the vertical components, the conversions are emphasized
by canceling the part of the response that are common to both
components. A member of different styles of such deconvolution, are
investigated and a variant of the multitaper method is adopted for
subsequent applications. The TASMAL experiment 2003-2005
spans the expected location of the transition between Precambrian and
Phanerozoic Australia. The 20 portable broadband stations were
exploited in receiver function studies to extract S wave crustal
structure through the inversion of stacked receiver functions using the
Neighbourhood Algorithm. There is no clear crustal transition
associated with the presence of Tasman Line. The Precambrian Cratons
tend to exhibit crustal thicknesses close to 40 km but such values
are also found in some Phanerozoic sites.
¶
The second part of the thesis is directed at the exploitation of
ambient noise or seismic coda to gain information on the Green's
function between seismic stations. The TASMAL experiment
covered a significant fraction of the Australian continent with a
simultaneous deployment of portable broadband stations. From these
continuous records, it has proved possible to extract very clear
Rayleigh wave signals for station separations up to 2000 km, and to
demonstrate the frequency dependent variations in group velocity
behaviour. The combination of the paths between the 20 stations localize such
behaviour, but detailed images needed more data. The entire archive of
portable broadband data recorded by RSES was mined, and
combined with data from permanent stations to provide more than 1100
estimates of interstation Green's functions within Australia. Group
velocity analysis as function of frequency was followed by nonlinear
tomography with the Fast Marching Method. The resulting images of
group velocity patterns as a function frequency show pronounced regions
of lowered group velocities, most of which match regions of thick
sediment. The frequency dependence is not consistent with just
sedimentary structure and low midcrustal velocities, most likely due
to elevated temperatures, are also needed.
¶
The surface wave portion of the interstation Green's function is the
most energetic, and is normally all that seen in ambient noise
studies. However, in the coda of events record at the broadband
Warramunga seismic array in the Northern Territory, the P and S
body wave components also emerge. The characteristics of these
arrivals match those observed from
nearby small earthquakes. The stacked cross-correlation is the normal
approach to enhance Green's function information from ambient noise,
but a broader spectral band width with the same phase response can be
found by spectral division. It appears advantageous to compare both
approaches and select the best result, since very little modifications
to procedures are needed.
¶
The properties of the ambient noise at a single station have been
investigated in the logarithmic spectral domain and a station
dependent signal can be extracted by stacking. The signal appears to
be related to the local structure beneath the station, and when fully
characterized may provide a new means of investigating structure.
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Seismic tomography in western Washington /Lees, Jonathan Matthew, January 1989 (has links)
Thesis (Ph. D.)--University of Washington, 1989. / Vita. Includes bibliographical references.
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Applications of global seismic tomography and analysis of variational methods for the solution of the linearly attenuating frequency domain wave equation /Johnson, Stuart G., January 1997 (has links)
Thesis (Ph. D.)--University of California, San Diego, 1997. / Vita. Includes bibliographical references.
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Seismic velocity structure of the Puget Sound Region from 3-D non-linear tomography /Symons, Neill. January 1998 (has links)
Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (p. [148]-158).
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Modeling and migration of Hibernia seismic data /Kelly, Irene G., January 1998 (has links)
Thesis (M. Sc.), Memorial University of Newfoundland, 1998. / Bibliography: leaves 108-111. Also available online.
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Fault imaging of Hibernia three-dimensional seismic data using edge detection and coherency measures /Carter, Nicholle Anna Gladys, January 1999 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 1999. / Bibliography: leaves 97-99. Also available online.
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Studies of the crust-mantle system beneath Southern CaliforniaHumphreys, Eugene Drake. January 1985 (has links)
Thesis (Ph. D.)--California Institute of Technology, 1985. / Typescript (photocopy). Includes bibliographical references (leaves 183-189).
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Application of borehole radar and Fresnel volume tomography to characterize a heterogeneous alluvial aquifer /Buursink, Marc Leonard. January 2006 (has links)
Thesis (Ph. D.)--Boise State University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 227-240). Also available online via the ProQuest Digital Dissertations database.
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Fresnel volume ground penetrating radar attenuation difference tomography and incorporating geostatistical constraints in nonlinear inverse problems /Johnson, Timothy Chad. January 2006 (has links)
Thesis (Ph. D.)--Boise State University, 2006. / Includes abstract. Includes bibliographical references (leaves 122-127). Also available online via the ProQuest Digital Dissertations database.
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Seismic tomography as an instrument for structural evaluation in the Printzsköld and Alliansen ore bodies, MalmbergetJonsson, Linus January 2017 (has links)
The Malmberget deposit is one of the major apatite iron ores in Europe, located in northern Norrbotten. As the mining in Malmberget proceeds deeper more challenges with the stability have been faced. When the stress distribution of a rock mass exceeds the rock strength energy in form of seismic waves is released. In Malmberget, a monitoring system consisting of 200 geophones is installed which detects all seismic waves in the area. Based on data received from the monitoring system, LKAB has achieved to generate a seismic tomography model over the velocity variations of the seismic waves as they propagate in the rock mass. The present study evaluates how the seismic tomography model can be used as a tool for reconstructing the structural characteristics of the two ore bodies Printzsköld and Alliansen. The aim is to clarify how seismic tomography can be combined with structural data to increase the geological knowledge of the Malmberget mining area. Based on structural measurements from the mine in combination with geotechnical data (RQD, Jr, Ja) two structural geological models were constructed. One model visualizing the orientation of the foliation and the other presenting brittle joints and fractures. The models were constructed in order to compare them with the seismic tomography model to outline structures and characteristics in the rock mass. The foliation in Printzsköld has a steep NE-SW orientation. In the eastern part where Printzsköld connects to Alliansen, the orientation changes to NW-SE, indicative of a fold structure. The joints and fractures in the study area appeared as 4 sets. One set appeared parallel to the foliation and one perpendicular to it. The two other sets were oriented E-W almost perpendicular to each other with a shallow dip. The rock quality in Printzsköld shows a pattern of increasing quality deeper down with zones of lower quality following the magnetite ore body. The previous identified deformation zone DZ031 appear as an important structure for unstable zones in Printzsköld. The current results suggest that the seismic tomography model needs more investigation but shows promising results as an indicative instrument delineating large scale structures and large zones with lower rock quality. / Gruvan i Malmberget är belägen i norra Norrbotten och utgör en av de största apatitjärnmalmerna i Europa. Med tiden försätter brytningen i Malmberget på allt större djup. Det innebär en större utmaning med stabiliteten i gruvan då spänningarna i berget kan tänkas öka längre ner. När bergsspänningarna överskrider bergets hållfasthet sker en frigörelse av energi i form av seismiska vågor. I Malmberget finns ett system av 200 geofoner som detekterar alla seismiska vågor i området. Baserat på data som mottagits från övervakningssystemet har LKAB lyckats framställa en seismisk tomografimodell över de seismiska vågornas hastighetsvariationer när de breder ut sig i bergmassan. I studien granskas hur den seismiska tomografin kan användas som ett verktyg för att utvärdera geologiska strukturer i de två malmkropparna Printzsköld och Alliansen. Syftet är att klargöra om seismisk tomografi kan kombineras med strukturdata för att öka den geologiska kunskapen i Malmbergets gruvområde. På basis av mätta strukturer i gruvan i kombination med geoteknisk data (RQD, Jr, Ja) konstruerades två strukturgeologiska modeller i syfte att jämföra modellerna mot den seismiska tomografin. Resultatet från studien visar att foliationen i Printzsköld har en NÖ-SV orientering med en brant stupning. I den östra delen som förbinder till Alliansen ändras orienteringen succesivt till NV-SÖ, vilket indikerar en veckning av foliationen. De dominerande riktningarna för sprickor och frakturer i Printzsköld och Alliansen uppträdde som 4 set. Ett set var orienterat parallellt med foliationen och ett vinkelrätt mot det förevarande. De två andra sprick riktningarna var orienterade Ö-V nästintill vinkelrätt mot varandra med en flack stupning. Bergskvalitén i Printzsköld visade ett mönster av att förbättras djupare ner. Zoner med lägre bergskvalité följer malmkroppen. Den seismiska tomografin uppvisade korrelation med storskaliga strukturer samt stora områden med minskad berghållfasthet. Den tidigare identifierade deformations zonen DZ031 uppträder också som en viktig struktur instabila områden i Printzsköld. Utvärderandet av resultaten tyder på att den seismiska tomografin behöver fortsatt mer undersökningsarbete men visar lovande resultat av att fungera som ett vägledande instrument för att definiera storskaliga strukturer och större områden med sämre bergskvalité.
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