olafur gudmundsson - Academia.edu (original) (raw)

Uploads

Papers by olafur gudmundsson

Research paper thumbnail of ScanArray—A Broadband Seismological Experiment in the Baltic Shield

Seismological Research Letters

The ScanArray international collaborative program acquired broadband seismological data at 192 lo... more The ScanArray international collaborative program acquired broadband seismological data at 192 locations in the Baltic Shield during the period between 2012 and 2017. The main objective of the program is to provide seismological constraints on the structure of the lithospheric crust and mantle as well as the sublithospheric upper mantle. The new information will be applied to studies of how the lithospheric and deep structure affect observed fast topographic change and geological-tectonic evolution of the region. The program also provides new information on local seismicity, focal mechanisms, and seismic noise. The recordings are generally of very high quality and are used for analysis by various seismological methods, including P- and S-wave receiver functions for the crust and upper mantle, surface wave and ambient noise inversion for seismic velocity, body-wave P- and S-wave tomography for upper mantle velocity structure using ray and finite frequency methods, and shear-wave spli...

Research paper thumbnail of A Probabilistic Tremor Location Method

Geophysical Research Letters

Research paper thumbnail of Seismicity of the Hengill area, SW Iceland: Details revealed by catalog relocation and collapsing

Journal of Volcanology and Geothermal Research

Research paper thumbnail of Locating tremor using stacked products of correlations

Geophysical Research Letters

Research paper thumbnail of Ambient-noise tomography of Katla volcano, south Iceland

Journal of Volcanology and Geothermal Research

Research paper thumbnail of The dense root of the Iceland crust

Research paper thumbnail of Three-dimensional empiritraveltimes: construction and applications

Research paper thumbnail of The May 29(th) 2008 earthquake aftershock sequence within the South Iceland Seismic Zone : Fault locations and source parameters of aftershocks

Jokull, 2010

Page 1. Reviewed research article The May 29th 2008 earthquake aftershock sequence within the Sou... more Page 1. Reviewed research article The May 29th 2008 earthquake aftershock sequence within the South Iceland Seismic Zone: Fault locations and source parameters of aftershocks Bryndís Brandsdóttir1, Matthew Parsons2 ...

Research paper thumbnail of Some problems in global tomography: modeling the core-mantle boundary and statistical analysis of travel-time data

Research paper thumbnail of Seismic tomography in Greenland from the dispersion of Love waves

ABSTRACT The GLATIS project (Greenland Lithosphere Analysed Teleseismically on the Ice Sheet) was... more ABSTRACT The GLATIS project (Greenland Lithosphere Analysed Teleseismically on the Ice Sheet) was started in 1999 with the aim to analyse the crust and upper mantle of Greenland. 16 temporary broadband seismic stations have been collecting data in Greenland for periods varying from few months to several years; of these four are placed on the ice sheet. This temporary network has, together with four permanent broadband seismic stations in Greenland, provided data for the project. The GLATIS project is designed to determine the lithospheric structure from a combination of receiver function analysis and surface wave analysis. The present study makes use of Love wave dispersion to obtain information about the velocity structure of the crust and upper mantle. Average Love wave phase velocity dispersion curves along great circle paths crossing Greenland have been calculated by the two-station method. Phase velocities have been determined for Love wave periods between 30 and 100 s, covering the region from the surface of Earth down to approximately 500 km. The resulting velocities are plotted in a series of maps showing a colour coded phase velocity along the great circle paths for fixed periods. Besides, the phase velocities have been used as input for a 2D isotropic inversion, again keeping the period fixed. Data coverage is sparse, giving only a rough picture of the crust and upper mantle structure in the study area. Results indicate a division of the crust into two areas with high crustal velocities in the northern part of the study area and lower velocities in the southern part. For the upper mantle, velocities are higher in the central part of the study area than in the northern and southern parts.

Research paper thumbnail of Variations of shear-wave splitting in Greenland: Mantle anisotropy and possible impact of the Iceland plume

Tectonophysics, Dec 1, 2008

... Azimuthal anisotropy is caused by the orientation of upper-mantle minerals (eg Nicolas and Ch... more ... Azimuthal anisotropy is caused by the orientation of upper-mantle minerals (eg Nicolas and Christensen, 1987), mainly olivine, which is both highly anisotropic and develops strain-induced lattice-preferred orientation (LPO) (eg, [Hess, 1964], [Vinnik et al., 1992] and [Silver, 1996 ...

Research paper thumbnail of Earthquake location via the direct use of arrival time catalogues

Egs Agu Eug Joint Assembly, Apr 1, 2003

ABSTRACT

Research paper thumbnail of GPS-analyse af jordskælvet - flyttede Sumatra sig virkelig 36 meter?

Research paper thumbnail of Monitoring of Acoustic Emissions Within Geothermal Areas in Iceland: A new Tool for Geothermal Exploration

ABSTRACT With increased emphasis on geothermal development new exploration methods are needed in ... more ABSTRACT With increased emphasis on geothermal development new exploration methods are needed in order to improve general understanding of geothermal reservoirs, characterize their extent and assess the potential for sustainable power production. Monitoring of acoustic emissions within geothermal areas may provide a new tool to evaluate the spatial extent of geothermal fields and model rock-fluid interactions. Three-dimensional seismic data have been used to assess the spatial and temporal distribution of noise within several high-temperature geothermal fields in Iceland. Seismic noise in the 4-6 Hz range within the Svartsengi field can be attributed to steam hydraulics and pressure oscillations within the geothermal reservoirs. Seismic noise surveys compliment electrical resistivity soundings and TEM-surveys by providing information pertinent to the current geothermal activity and extent of steam fields within the uppermost crust of the geothermal reservoir. Information related to acoustic emissions can thus help define targets for future wells.

Research paper thumbnail of A Quantitative Method to Map the Source Distribution of Microseisms Using Noise Covariograms

Research paper thumbnail of Geothermal noise at Olkelduhals, SW Iceland

Research paper thumbnail of Rayleigh wave tomography of the Greenland Shield

We investigate the lithospheric structure beneath Greenland using teleseismic Rayleigh waves reco... more We investigate the lithospheric structure beneath Greenland using teleseismic Rayleigh waves recorded by 20 broadband seismograph stations deployed across Greenland. This study forms part of the ongoing `GLATIS' project. Phase velocity curves are generated for paths between pairs of seismograph stations, using the two-station method of Gomberg et al. (1988). More than 30 paths across Greenland have been analysed, giving

Research paper thumbnail of The May 29 2008 earthquake aftershock sequence within the South Iceland Seismic Zone: Fault locations and source parameters of aftershocks

The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. The South Ice... more The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. The South Iceland Seismic Zone (SISZ) is a complex transform zone where left-lateral E-W shear between the Reykjanes Peninsula Rift Zone and the Eastern Volcanic Zone is accommodated by bookshelf faulting along N-S lateral strike-slip faults. The SISZ is also a transient feature, migrating sideways in response

Research paper thumbnail of GPS analyses of the Sumatra-Andaman earthquake

Eos, Transactions American Geophysical Union, 2005

Research paper thumbnail of Broadband observations of upper-mantle seismic phases in northern Australia and the attenuation structure in the upper mantle

Physics of the Earth and Planetary Interiors, 1994

Research paper thumbnail of ScanArray—A Broadband Seismological Experiment in the Baltic Shield

Seismological Research Letters

The ScanArray international collaborative program acquired broadband seismological data at 192 lo... more The ScanArray international collaborative program acquired broadband seismological data at 192 locations in the Baltic Shield during the period between 2012 and 2017. The main objective of the program is to provide seismological constraints on the structure of the lithospheric crust and mantle as well as the sublithospheric upper mantle. The new information will be applied to studies of how the lithospheric and deep structure affect observed fast topographic change and geological-tectonic evolution of the region. The program also provides new information on local seismicity, focal mechanisms, and seismic noise. The recordings are generally of very high quality and are used for analysis by various seismological methods, including P- and S-wave receiver functions for the crust and upper mantle, surface wave and ambient noise inversion for seismic velocity, body-wave P- and S-wave tomography for upper mantle velocity structure using ray and finite frequency methods, and shear-wave spli...

Research paper thumbnail of A Probabilistic Tremor Location Method

Geophysical Research Letters

Research paper thumbnail of Seismicity of the Hengill area, SW Iceland: Details revealed by catalog relocation and collapsing

Journal of Volcanology and Geothermal Research

Research paper thumbnail of Locating tremor using stacked products of correlations

Geophysical Research Letters

Research paper thumbnail of Ambient-noise tomography of Katla volcano, south Iceland

Journal of Volcanology and Geothermal Research

Research paper thumbnail of The dense root of the Iceland crust

Research paper thumbnail of Three-dimensional empiritraveltimes: construction and applications

Research paper thumbnail of The May 29(th) 2008 earthquake aftershock sequence within the South Iceland Seismic Zone : Fault locations and source parameters of aftershocks

Jokull, 2010

Page 1. Reviewed research article The May 29th 2008 earthquake aftershock sequence within the Sou... more Page 1. Reviewed research article The May 29th 2008 earthquake aftershock sequence within the South Iceland Seismic Zone: Fault locations and source parameters of aftershocks Bryndís Brandsdóttir1, Matthew Parsons2 ...

Research paper thumbnail of Some problems in global tomography: modeling the core-mantle boundary and statistical analysis of travel-time data

Research paper thumbnail of Seismic tomography in Greenland from the dispersion of Love waves

ABSTRACT The GLATIS project (Greenland Lithosphere Analysed Teleseismically on the Ice Sheet) was... more ABSTRACT The GLATIS project (Greenland Lithosphere Analysed Teleseismically on the Ice Sheet) was started in 1999 with the aim to analyse the crust and upper mantle of Greenland. 16 temporary broadband seismic stations have been collecting data in Greenland for periods varying from few months to several years; of these four are placed on the ice sheet. This temporary network has, together with four permanent broadband seismic stations in Greenland, provided data for the project. The GLATIS project is designed to determine the lithospheric structure from a combination of receiver function analysis and surface wave analysis. The present study makes use of Love wave dispersion to obtain information about the velocity structure of the crust and upper mantle. Average Love wave phase velocity dispersion curves along great circle paths crossing Greenland have been calculated by the two-station method. Phase velocities have been determined for Love wave periods between 30 and 100 s, covering the region from the surface of Earth down to approximately 500 km. The resulting velocities are plotted in a series of maps showing a colour coded phase velocity along the great circle paths for fixed periods. Besides, the phase velocities have been used as input for a 2D isotropic inversion, again keeping the period fixed. Data coverage is sparse, giving only a rough picture of the crust and upper mantle structure in the study area. Results indicate a division of the crust into two areas with high crustal velocities in the northern part of the study area and lower velocities in the southern part. For the upper mantle, velocities are higher in the central part of the study area than in the northern and southern parts.

Research paper thumbnail of Variations of shear-wave splitting in Greenland: Mantle anisotropy and possible impact of the Iceland plume

Tectonophysics, Dec 1, 2008

... Azimuthal anisotropy is caused by the orientation of upper-mantle minerals (eg Nicolas and Ch... more ... Azimuthal anisotropy is caused by the orientation of upper-mantle minerals (eg Nicolas and Christensen, 1987), mainly olivine, which is both highly anisotropic and develops strain-induced lattice-preferred orientation (LPO) (eg, [Hess, 1964], [Vinnik et al., 1992] and [Silver, 1996 ...

Research paper thumbnail of Earthquake location via the direct use of arrival time catalogues

Egs Agu Eug Joint Assembly, Apr 1, 2003

ABSTRACT

Research paper thumbnail of GPS-analyse af jordskælvet - flyttede Sumatra sig virkelig 36 meter?

Research paper thumbnail of Monitoring of Acoustic Emissions Within Geothermal Areas in Iceland: A new Tool for Geothermal Exploration

ABSTRACT With increased emphasis on geothermal development new exploration methods are needed in ... more ABSTRACT With increased emphasis on geothermal development new exploration methods are needed in order to improve general understanding of geothermal reservoirs, characterize their extent and assess the potential for sustainable power production. Monitoring of acoustic emissions within geothermal areas may provide a new tool to evaluate the spatial extent of geothermal fields and model rock-fluid interactions. Three-dimensional seismic data have been used to assess the spatial and temporal distribution of noise within several high-temperature geothermal fields in Iceland. Seismic noise in the 4-6 Hz range within the Svartsengi field can be attributed to steam hydraulics and pressure oscillations within the geothermal reservoirs. Seismic noise surveys compliment electrical resistivity soundings and TEM-surveys by providing information pertinent to the current geothermal activity and extent of steam fields within the uppermost crust of the geothermal reservoir. Information related to acoustic emissions can thus help define targets for future wells.

Research paper thumbnail of A Quantitative Method to Map the Source Distribution of Microseisms Using Noise Covariograms

Research paper thumbnail of Geothermal noise at Olkelduhals, SW Iceland

Research paper thumbnail of Rayleigh wave tomography of the Greenland Shield

We investigate the lithospheric structure beneath Greenland using teleseismic Rayleigh waves reco... more We investigate the lithospheric structure beneath Greenland using teleseismic Rayleigh waves recorded by 20 broadband seismograph stations deployed across Greenland. This study forms part of the ongoing `GLATIS' project. Phase velocity curves are generated for paths between pairs of seismograph stations, using the two-station method of Gomberg et al. (1988). More than 30 paths across Greenland have been analysed, giving

Research paper thumbnail of The May 29 2008 earthquake aftershock sequence within the South Iceland Seismic Zone: Fault locations and source parameters of aftershocks

The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. The South Ice... more The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. The South Iceland Seismic Zone (SISZ) is a complex transform zone where left-lateral E-W shear between the Reykjanes Peninsula Rift Zone and the Eastern Volcanic Zone is accommodated by bookshelf faulting along N-S lateral strike-slip faults. The SISZ is also a transient feature, migrating sideways in response

Research paper thumbnail of GPS analyses of the Sumatra-Andaman earthquake

Eos, Transactions American Geophysical Union, 2005

Research paper thumbnail of Broadband observations of upper-mantle seismic phases in northern Australia and the attenuation structure in the upper mantle

Physics of the Earth and Planetary Interiors, 1994