Title Glossary of interest to earthquake and engineering
... amplification (by seismograph) Most earthquakes are relatively small, in fact, so small that no one feels them. In order for seismologists to see the recording of the ground movement from smaller earthquakes, the recording has to be made larger. Modern seismographs are able to magnify the ground mot ...
... amplification (by seismograph) Most earthquakes are relatively small, in fact, so small that no one feels them. In order for seismologists to see the recording of the ground movement from smaller earthquakes, the recording has to be made larger. Modern seismographs are able to magnify the ground mot ...
Lecture 18
... Galer and O’Nions (1985) concluded that something was very wrong with conventional views of t h e mantle. They suggested that Pb now in the upper mantle had not resided there for long, that it was ultimately derived from a lower mantle reservoir that had a primitive (i.e., chondritic) Th/U ratio. In ...
... Galer and O’Nions (1985) concluded that something was very wrong with conventional views of t h e mantle. They suggested that Pb now in the upper mantle had not resided there for long, that it was ultimately derived from a lower mantle reservoir that had a primitive (i.e., chondritic) Th/U ratio. In ...
Melt Generation at Very Slow-Spreading Oceanic Ridges
... significantly. Conversely, if there are continuous layers of ultramafic cumulates in the lower crust, their high seismic velocities would lead them to be classified as subMoho by seismic methods. The origin of the material above the Moho is much less well constrained than that below the Moho, becaus ...
... significantly. Conversely, if there are continuous layers of ultramafic cumulates in the lower crust, their high seismic velocities would lead them to be classified as subMoho by seismic methods. The origin of the material above the Moho is much less well constrained than that below the Moho, becaus ...
Deep structure of the Baikal rift zone revealed by joint inversion of
... has long been debated in intracontinental rift areas, particularly in the Baikal rift zone, Asia, which is colder than other continental rifts. As previous gravity and teleseismic studies support the dominance of opposing mechanisms in the Baikal rift, we reconsidered both data sets and jointly inve ...
... has long been debated in intracontinental rift areas, particularly in the Baikal rift zone, Asia, which is colder than other continental rifts. As previous gravity and teleseismic studies support the dominance of opposing mechanisms in the Baikal rift, we reconsidered both data sets and jointly inve ...
Non-chondritic sulphur isotope composition of the terrestrial mantle
... lack of correlation between d34S and 206Pb/204Pb (Supplementary Fig. 5), together with the preservation of the trends between d34S and Sr–Nd isotopes, argue in favour of relatively sulphur-poor HIMU and LOMU endmembers, overprinted by the contribution of a sulphur-rich enriched-mantle component. In ...
... lack of correlation between d34S and 206Pb/204Pb (Supplementary Fig. 5), together with the preservation of the trends between d34S and Sr–Nd isotopes, argue in favour of relatively sulphur-poor HIMU and LOMU endmembers, overprinted by the contribution of a sulphur-rich enriched-mantle component. In ...
Thematic Article Oceanic crust and Moho of the Pacific Plate in the
... Abstract To show the structure of oceanic crust and Moho around the eastern Ogasawara Plateau, we have analyzed industry-standard two-dimensional multichannel seismic reflection data. To obtain improved velocity models, phase information of seismic signals was used for velocity analysis and velocity ...
... Abstract To show the structure of oceanic crust and Moho around the eastern Ogasawara Plateau, we have analyzed industry-standard two-dimensional multichannel seismic reflection data. To obtain improved velocity models, phase information of seismic signals was used for velocity analysis and velocity ...
The Promise of Elastic Anisotropy
... Since most geophysical applications place the energy source on the surface, waves generally propagate vertically. Such waves are sensitive to TIH anisotropy, and are therefore useful for detecting vertically aligned fractures. Any stress field can also produce TIH anisotropy if the two horizontal st ...
... Since most geophysical applications place the energy source on the surface, waves generally propagate vertically. Such waves are sensitive to TIH anisotropy, and are therefore useful for detecting vertically aligned fractures. Any stress field can also produce TIH anisotropy if the two horizontal st ...
The fate of fluids released from subducting slab in
... earthquakes and to collision tectonics. An approximately 10 km thick lower crustal layer of low Poisson’s ratio (σ = 0.22) in the forearc is estimated to represent a maximum addition of ∼14 % by volume of quartz (σ = 0.09). If this quartz is removed from rising silica-saturated fluids over long time ...
... earthquakes and to collision tectonics. An approximately 10 km thick lower crustal layer of low Poisson’s ratio (σ = 0.22) in the forearc is estimated to represent a maximum addition of ∼14 % by volume of quartz (σ = 0.09). If this quartz is removed from rising silica-saturated fluids over long time ...
california state university, northridge rayleigh wave tomography
... boundary. Here, I present seismic results from a marine deployment of 34 ocean bottom seismometers offshore southern California, the ALBACORE (Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) project, to study the west and east side of the Pacifi ...
... boundary. Here, I present seismic results from a marine deployment of 34 ocean bottom seismometers offshore southern California, the ALBACORE (Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) project, to study the west and east side of the Pacifi ...
Crustal flow in Tibet: geophysical evidence for the physical state of
... Rosenberg & Handy 2005) means the relative strength of lower crust and upper mantle will vary in time and space, and that an evaluation of this relative strength requires detailed knowledge of the lithosphere. ...
... Rosenberg & Handy 2005) means the relative strength of lower crust and upper mantle will vary in time and space, and that an evaluation of this relative strength requires detailed knowledge of the lithosphere. ...
Alteration of the subducting oceanic lithosphere at the southern
... [1] Hydrothermal circulation and brittle faulting processes affecting the oceanic lithosphere are usually confined to the upper crust for oceanic lithosphere created at intermediate to fast spreading rates. Lower crust and mantle rocks are therefore relatively dry and undeformed. However, recent stu ...
... [1] Hydrothermal circulation and brittle faulting processes affecting the oceanic lithosphere are usually confined to the upper crust for oceanic lithosphere created at intermediate to fast spreading rates. Lower crust and mantle rocks are therefore relatively dry and undeformed. However, recent stu ...
Origins of the plume hypothesis and some of its
... Hawaii. Recycled oceanic crust melts first and reacts with surrounding peridotite to form pyroxenite. The pyroxenite then melts to form voluminous Ni-rich magmas. They obtain an excess temperature of 250-300 K. I reiterate the assumptions for the petrological grid to introduce alternatives to therma ...
... Hawaii. Recycled oceanic crust melts first and reacts with surrounding peridotite to form pyroxenite. The pyroxenite then melts to form voluminous Ni-rich magmas. They obtain an excess temperature of 250-300 K. I reiterate the assumptions for the petrological grid to introduce alternatives to therma ...
Vector wavefields for weakly attenuating anisotropic media by the
... of complex group velocity which are 100 times smaller than real parts. Therefore, we take the condition that imaginary parts of complex group velocity must be more than 100times smaller than real parts or the condition that the computed values of Q must be larger than 50 as a rough criterion of the ...
... of complex group velocity which are 100 times smaller than real parts. Therefore, we take the condition that imaginary parts of complex group velocity must be more than 100times smaller than real parts or the condition that the computed values of Q must be larger than 50 as a rough criterion of the ...
International Ocean Discovery Program Expedition 360 Scientific
... rock, locally knobby igneous outcrop surrounded on its periphery by a pavement of limestone (in some places ripple marked) and carbonate-cemented pebble conglomerate. Using the British Geological Survey’s 5 m diamond rock drill and 1 m BRIDGE oriented corer, MacLeod et al. (1998) drilled 42 successf ...
... rock, locally knobby igneous outcrop surrounded on its periphery by a pavement of limestone (in some places ripple marked) and carbonate-cemented pebble conglomerate. Using the British Geological Survey’s 5 m diamond rock drill and 1 m BRIDGE oriented corer, MacLeod et al. (1998) drilled 42 successf ...
The OIB paradox - Do plumes exist?
... (Hémond et al., 1993; Thirlwall et al., 2004) but there is strong Pb-isotope and trace-element evidence that the depleted component is not derived from the ambient upper mantle but instead forms an intrinsic part of the Iceland plume (Thirlwall, 1995; Fitton et al., 1997, 2003). This being so, Icel ...
... (Hémond et al., 1993; Thirlwall et al., 2004) but there is strong Pb-isotope and trace-element evidence that the depleted component is not derived from the ambient upper mantle but instead forms an intrinsic part of the Iceland plume (Thirlwall, 1995; Fitton et al., 1997, 2003). This being so, Icel ...
Target-oriented full waveform inversion of seismic data
... The conventional way to gain structural information about the earth is by acquisition and processing of seismic data. Seismic data is acquired by sending sound waves into the earth (for example by means of an explosion) and recording the sound that is reflected back towards the surface. The recording ...
... The conventional way to gain structural information about the earth is by acquisition and processing of seismic data. Seismic data is acquired by sending sound waves into the earth (for example by means of an explosion) and recording the sound that is reflected back towards the surface. The recording ...
(2005, April). Beyond the thermal plume paradigm. Geophys. Res
... varies with depth (hlm = 7 1021 Pa s, hum = 7 1020 Pa s, in the astenosphere ha = 2 1020 Pa s) and with temperature, so that hot material may be two orders of magnitude less viscous than the surrounding mantle. At the surface we simulate a spreading ridge by imposing the velocity vx = 6 cm/yr, in or ...
... varies with depth (hlm = 7 1021 Pa s, hum = 7 1020 Pa s, in the astenosphere ha = 2 1020 Pa s) and with temperature, so that hot material may be two orders of magnitude less viscous than the surrounding mantle. At the surface we simulate a spreading ridge by imposing the velocity vx = 6 cm/yr, in or ...
Deep-mantle contributions to the surface dynamics of the North
... contrast between the very slow western margin of North America and the much faster eastern and central portion of the continent. Below the continental high-velocity root, centred under the Canadian Shield at a depth of about 250 km, there is a transition to shorter-wavelength structures, notably the ...
... contrast between the very slow western margin of North America and the much faster eastern and central portion of the continent. Below the continental high-velocity root, centred under the Canadian Shield at a depth of about 250 km, there is a transition to shorter-wavelength structures, notably the ...
Chapter 3. Transitions Between Electronic States
... Ψ1 and Ψ2 by making a good guess at the interaction operator, P1 → 2, that perturbs the initial state wave function Ψ1 and makes it “look like” the wavefunction of the final state Ψ2. Knowledge of and Ψ1, Ψ2 and P1 → 2 allows the computation of the rate of transition between the two states by compu ...
... Ψ1 and Ψ2 by making a good guess at the interaction operator, P1 → 2, that perturbs the initial state wave function Ψ1 and makes it “look like” the wavefunction of the final state Ψ2. Knowledge of and Ψ1, Ψ2 and P1 → 2 allows the computation of the rate of transition between the two states by compu ...
(PPT, 285KB)
... He fundamentally defined his arbitrary orientation for the cell as being that in which the internal current would run parallel to and in the same direction as a hypothetical magnetizing current loop around the local line of latitude which would induce a magnetic dipole field oriented like the Earth' ...
... He fundamentally defined his arbitrary orientation for the cell as being that in which the internal current would run parallel to and in the same direction as a hypothetical magnetizing current loop around the local line of latitude which would induce a magnetic dipole field oriented like the Earth' ...
Magnetotellurics
Magnetotellurics (MT) is an electromagnetic geophysical method for inferring the earth's subsurface electrical conductivity from measurements of natural geomagnetic and geoelectric field variation at the Earth's surface. Investigation depth ranges from 300m below ground by recording higher frequencies down to 10,000m or deeper with long-period soundings. Developed in the USSR and France during the 1950s, MT is now an international academic discipline and is used in exploration surveys around the world. Commercial uses include hydrocarbon (oil and gas) exploration, geothermal exploration, mining exploration, as well as hydrocarbon and groundwater monitoring. Research applications include experimentation to further develop the MT technique, long-period deep crustal exploration, and earthquake precursor prediction research.