2,941 research outputs found
Global Mapping of the Uppermantle by Surface Wave Tomography
Surface wave tomography compliments detailed body
wave studies by providing a global framework for the lateral variability
of the uppermantle. In particular the method allows one to
map the mantle beneath the lithosphere and to discuss the fate of
overridden oceanic plates. Midocean ridges appear to extend to at
least 400 km. By contrast, the very high velocities associated with
shields are primarily much shallower. The Red Sea-Afar region is a
pronounced and deep low-velocity anomaly. A significant uppermantle
anomaly has been found in the central Pacific. This
"Polynesian Anomaly" is surrounded by hotspots; Hawaii, Tahiti,
Samoa and the Caroline Islands. This may be the site of the extensive
Cretaceous volanism which generated the plateaus and
seamounts in the western Pacific. Anisotropy indicates deep upwellings,
>300 km depth, under midocean ridges, the Afar and the
Polynesian Anomaly and downwelling under the western Pacific and
the northeastern Indian Ocean. The large fast anomaly under the
south Atlantic may represent overridden Pacific plate
Neutrino mixing and masses from long baseline and atmospheric oscillation experiments
We argue that regardless of the outcome of future Long Baseline experiments,
additional information will be needed to unambiguously decide among the
different scenarios of neutrino mixing. We use, for this purpose, a simple test
of underground data: an asymmetry between downward and upward going events.
Such an asymmetry, in which matter effects can be crucial, tests electron and
muon neutrino data separately and can be compared with the theoretical
prediction without relying on any simulation program.Comment: 9 pages, 2 figures (eps
Migration and Settlement: 11. Poland
As part of the comparative quantitative assessment of recent migration patterns and spatial population dynamics of IIASA's 17 National Member Organization countries, this report analyzes the changing population patterns in Poland and their relations to spatial policy. The analysis focuses on regional interdependence and the role of major urban agglomerations in Poland's spatial population system
Geophysical aspects of very long baseline neutrino experiments
Several proposed experiments will send beams of neutrinos through the Earth
along paths with a source-receiver distance of hundreds or thousands of
kilometers. Knowledge of the physical properties of the medium traversed by
these beams, in particular the density, will be necessary in order to properly
interpret the experimental data. Present geophysical knowledge allows the
average density along a path with a length of several thousand km to be
estimated with an accuracy of about per cent. Physicists planning
neutrino beam experiments should decide whether or not this level of
uncertainty is acceptable. If greater accuracy is required, intensive
geophysical research on the Earth structure along the beam path should be
conducted as part of the preparatory work on the experiments.Comment: 8 pages, uses elsart.cls. Talk given at 3rd International Workshop on
Neutrino Factory based on Muon Storage Rings (NuFACT'01), Tsukuba, Japan,
24-30 May 200
A new method for determining the long‐period component of the source time function of large earthquakes
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94826/1/grl4270.pd
Neutrino parameters from matter effects in at long baselines
We show that the earth matter effects in the
survival probability can be used to cleanly determine the third leptonic mixing
angle and the sign of the atmospheric neutrino mass squared
difference, , using a -beam as a source.Comment: 4 pages, 4 eps figures; comments and references added, to appear in
Phys. Rev.
Core-mantle boundary deformations and J2 variations resulting from the 2004 Sumatra earthquake
The deformation at the core-mantle boundary produced by the 2004 Sumatra
earthquake is investigated by means of a semi-analytic theoretical model of
global coseismic and postseismic deformation, predicting a millimetric
coseismic perturbation over a large portion of the core-mantle boundary.
Spectral features of such deformations are analysed and discussed. The
time-dependent postseismic evolution of the elliptical part of the gravity
field (J2) is also computed for different asthenosphere viscosity models. Our
results show that, for asthenospheric viscosities smaller than 10^18 Pa s, the
postseismic J2 variation in the next years is expected to leave a detectable
signal in geodetic observations.Comment: 14 pages, 8 figures, 1 table. It will appear in Geophysical Journal
Internationa
The Earth’s Interior: A New Frontier and a New Challenge for Earth Scientists
In this era of space exploration, deep expeditions to the
ocean bottom and far viewing telescopes, the Earth's interior
has emerged as one of the most challenging frontier
areas for scientific investigation. Exploration of the
crust, by seismic and other means, is well underway but
our view of the underlying mantle and core is fuzzy.
Plate tectonic theory has revolutionized Earth Science but
we still do not understand the driving mechanism or why
global processes change with time. The origins of the
magnetic field, volcanism, earthquakes, mineral resources
and mountain building processes are related to processes
in the deep interior. Planetary exploration has opened up
the new science of comparative planetology and yet, the
most fundamental questions regarding the origin, evolution
and composition of the Earth are unresolved because of our
ignorance of the characteristics of most of our planet, the
interior.
The time is now ripe to make an integrated study of the
Earth as a Planet or, in space age jargon, to undertake a
mission to Planet Earth. There are several recent developments
which make this timely
Report of the panel on earth structure and dynamics, section 6
The panel identified problems related to the dynamics of the core and mantle that should be addressed by NASA programs. They include investigating the geodynamo based on observations of the Earth's magnetic field, determining the rheology of the mantle from geodetic observations of post-glacial vertical motions and changes in the gravity field, and determining the coupling between plate motions and mantle flow from geodetic observations of plate deformation. Also emphasized is the importance of support for interdisciplinary research to combine various data sets with models which couple rheology, structure and dynamics
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