Transformation of earthquake displacement field for spherical earth

1971 ◽  
Vol 61 (2) ◽  
pp. 289-295 ◽  
Author(s):  
Hans R. Wason ◽  
Sarva Jit Singh
Keyword(s):  
Coordinate System ◽  
Displacement Field ◽  
Homogeneous Medium ◽  
Addition Theorem ◽  
Spherical Waves ◽  
The Earth ◽  
Spherical Earth ◽  
The Subject ◽  
Navier Equation

abstract An addition theorem for spherical waves is used to transform the displacement field due to an arbitrary shear dislocation in an unbounded homogeneous medium with origin at the focus to that in a coordinate system with origin at the center of the Earth. The final results are expressed in terms of the eigenvector solutions of the vector Naviér equation of dynamical elasticity. Some serious mistakes in recent papers on the subject have been pointed out.

Transformation of the earthquake displacement field for spherical earth—Static case

1971 ◽  
Vol 61 (4) ◽  
pp. 861-874
Author(s):  
Hans R. Wason ◽  
Sarva Jit Singh
Keyword(s):  
Displacement Field ◽  
Spherical Surface ◽  
Homogeneous Medium ◽  
Addition Theorem ◽  
Polar Coordinate System ◽  
Earth Model ◽  
Static Case ◽  
Spherical Earth ◽  
Polar Coordinate ◽  
Internal Sources

abstract Explicit expressions for the static displacement field for a Volterra dislocation and a center of compression in an infinite homogeneous medium are obtained. Using an addition theorem, the field is transformed to a polar coordinate system with origin at the center of the Earth. Expressions for the discontinuity in the motion stress vector across the concentric spherical surface through the source are then obtained. These results can be used in studying the deformation of a multilayered spherical earth model induced by internal sources by the Thomson-Haskell matrix method which has so far been mostly applied to dynamic problems.

2.1. Working Group 1: Requirements for Coordinate Systems for Earth Dynamics

1975 ◽  
Vol 26 ◽  
pp. 15-20
Keyword(s):  
Coordinate System ◽  
Working Group ◽  
Global Scale ◽  
Coordinate Systems ◽  
Tectonic Plates ◽  
The Earth ◽  
International Projects ◽  
The Subject ◽  
Earth Dynamics ◽  
Group 1

As initial guidance for its deliberations, Working Group 1 accepted the objective implied in the Colloquium title and the more explicit description contained in the First Circular announcing the Colloquium:Earth dynamics is currently the subject of intensive world-wide research efforts. As a consequence of the new insights into Earth dynamics and acceptance of the hypothesis of moving tectonic plates, as well as the ability to measure crustal motions on a global scale with a precision of a few centimeters, a number of national and international projects have been organized to pursue these investigations. In all these efforts, a common feature is the necessity for a very well defined coordinate system to which all observations can be referred and in which theories can be formulated. At this time there is no widely accepted coordinate system in the Earth or in space which is defined with the precision needed for ongoing geodynamics research.

Reference Coordinate System Requirements for Geophysics

1975 ◽  
Vol 26 ◽  
pp. 87-92
Author(s):  
P. L. Bender
Keyword(s):  
Coordinate System ◽  
Polar Motion ◽  
Main Part ◽  
Measurement Techniques ◽  
Reference Points ◽  
Angular Motion ◽  
Coordinate Systems ◽  
Axis Of Rotation ◽  
The Earth ◽  
Fixed System

AbstractFive important geodynamical quantities which are closely linked are: 1) motions of points on the Earth’s surface; 2)polar motion; 3) changes in UT1-UTC; 4) nutation; and 5) motion of the geocenter. For each of these we expect to achieve measurements in the near future which have an accuracy of 1 to 3 cm or 0.3 to 1 milliarcsec.From a metrological point of view, one can say simply: “Measure each quantity against whichever coordinate system you can make the most accurate measurements with respect to”. I believe that this statement should serve as a guiding principle for the recommendations of the colloquium. However, it also is important that the coordinate systems help to provide a clear separation between the different phenomena of interest, and correspond closely to the conceptual definitions in terms of which geophysicists think about the phenomena.In any discussion of angular motion in space, both a “body-fixed” system and a “space-fixed” system are used. Some relevant types of coordinate systems, reference directions, or reference points which have been considered are: 1) celestial systems based on optical star catalogs, distant galaxies, radio source catalogs, or the Moon and inner planets; 2) the Earth’s axis of rotation, which defines a line through the Earth as well as a celestial reference direction; 3) the geocenter; and 4) “quasi-Earth-fixed” coordinate systems.When a geophysicists discusses UT1 and polar motion, he usually is thinking of the angular motion of the main part of the mantle with respect to an inertial frame and to the direction of the spin axis. Since the velocities of relative motion in most of the mantle are expectd to be extremely small, even if “substantial” deep convection is occurring, the conceptual “quasi-Earth-fixed” reference frame seems well defined. Methods for realizing a close approximation to this frame fortunately exist. Hopefully, this colloquium will recommend procedures for establishing and maintaining such a system for use in geodynamics. Motion of points on the Earth’s surface and of the geocenter can be measured against such a system with the full accuracy of the new techniques.The situation with respect to celestial reference frames is different. The various measurement techniques give changes in the orientation of the Earth, relative to different systems, so that we would like to know the relative motions of the systems in order to compare the results. However, there does not appear to be a need for defining any new system. Subjective figures of merit for the various system dependon both the accuracy with which measurements can be made against them and the degree to which they can be related to inertial systems.The main coordinate system requirement related to the 5 geodynamic quantities discussed in this talk is thus for the establishment and maintenance of a “quasi-Earth-fixed” coordinate system which closely approximates the motion of the main part of the mantle. Changes in the orientation of this system with respect to the various celestial systems can be determined by both the new and the conventional techniques, provided that some knowledge of changes in the local vertical is available. Changes in the axis of rotation and in the geocenter with respect to this system also can be obtained, as well as measurements of nutation.

“The heart above the ruins”: Miriam Waddington’s Poetry, the Spanish Civil War, and Jewish Canadian Literature

1969 ◽  
Vol 26 ◽  
Author(s):  
Emily Robins Sharpe
Keyword(s):  
Human Rights ◽  
World War Ii ◽  
Civil War ◽  
Spanish Civil War ◽  
World War ◽  
Canadian Literature ◽  
The Earth ◽  
The Holocaust ◽  
The Subject ◽  
War Consequences

The Jewish Canadian writer Miriam Waddington returned repeatedly to the subject of the Spanish Civil War, searching for hope amid the ruins of Spanish democracy. The conflict, a prelude to World War II, inspired an outpouring of literature and volunteerism. My paper argues for Waddington’s unique poetic perspective, in which she represents the Holocaust as the Spanish Civil War’s outgrowth while highlighting the deeply personal repercussions of the war – consequences for women, for the earth, and for community. Waddington’s poetry connects women’s rights to human rights, Canadian peace to European war, and Jewish persecution to Spanish carnage.

scholarly journals Children’s Astronomy. Development of the Shape of the Earth Concept in Polish Children between 5 and 10 Years of Age

2021 ◽  
Vol 11 (2) ◽  
pp. 75
Author(s):  
Jan Amos Jelinek
Keyword(s):  
Mental Model ◽  
Cultural Influences ◽  
Test Results ◽  
The Earth ◽  
Spherical Earth ◽  
The Individual ◽  
High Level ◽  
Cognitive Problems ◽  
Teaching Situations ◽  
Model Approach

The Earth’s shape concept develops as consecutive cognitive problems (e.g., the location of people and trees on the spherical Earth) are gradually resolved. Establishing the order of problem solving may be important for the organisation of teaching situations. This study attempted to determine the sequence of problems to be resolved based on tasks included in the EARTH2 test. The study covered a group of 444 children between 5 and 10 years of age. It captured the order in which children solve cognitive problems on the way to constructing a science-like concept. The test results were compared with previous studies. The importance of cultural influences connected to significant differences (24%) in test results was emphasised. Attention was drawn to the problem of the consistency of the mental model approach highlighted in the literature. The analysis of the individual sets of answers provided a high level of consistency of indications referring to the same model (36%), emphasising the importance of the concept of mental models.

scholarly journals V.—Further Excavations at Lanuvium

Archaeologia ◽  
1892 ◽  
Vol 53 (1) ◽  
pp. 147-154
Author(s):  
Lord Savile
Keyword(s):  
The Earth ◽  
The Subject

Since the last communication on the subject of my excavations at Lanuvium, which the Society of Antiquaries did me the honour to publish in 1886, those excavations have been carried on continuously, but very slowly, in consequence of the difficulties arising from the necessity of devising some means for disposing of the earth extracted in the course of excavation.

The Terrestrial Coordinate System and International Earth-rotation Services

1985 ◽  
Vol 38 (02) ◽  
pp. 216-217
Author(s):  
G. A. Wilkins
Keyword(s):  
Coordinate System ◽  
Earth Rotation ◽  
Reference System ◽  
New Techniques ◽  
Crustal Movements ◽  
Earth Observations ◽  
The Earth ◽  
External Reference ◽  
External Objects ◽  
Rotation Of The Earth

New techniques of measurement make it possible in 1984 to determine positions on the surface of the Earth to a much higher precision than was possible in 1884. If we look beyond the requirements of navigation we can see useful applications of global geodetic positioning to centimetric accuracy for such purposes as the control of mapping and the study of crustal movements. These new techniques depend upon observations of external objects, such as satellites or quasars rather than stars, and they require that the positions of these objects and the orientation of the surface of the Earth are both known with respect to an appropriate external reference system that is ‘fixed’ in space. We need networks of observing stations and analysis centres that monitor the motions of the external objects and the rotation of the Earth. Observations of stars by a transit circle are no longer adequate for this purpose.

Convection tectonics: some possible effects upon the Earth's surface of flow from the deep mantle

1988 ◽  
Vol 25 (8) ◽  
pp. 1199-1208 ◽  
Author(s):  
J. Tuzo Wilson
Keyword(s):  
Land Surface ◽  
Angle Of Incidence ◽  
Gulf Of Aden ◽  
Upward Flow ◽  
New Techniques ◽  
Ocean Ridges ◽  
The Earth ◽  
Mid Ocean Ridge ◽  
The Subject ◽  
Ocean Ridge

Until a little more than a century ago the land surface not only was the only part of the Earth accessible to humans but also was the only part for which geophysical and geochemical methods could then provide any details. Since then scientists have developed ways to study the ocean floors and some details of the interior of the Earth to ever greater depths. These discoveries have followed one another more and more rapidly, and now results have been obtained from all depths of the Earth.New methods have not contradicted or greatly disturbed either old methods or old results. Hence, it has been easy to overlook the great importance of these recent findings.Within about the last 5 years the new techniques have mapped the pattern of convection currents in the mantle and shown that these rise from great depths to the surface. Even though the results are still incomplete and are the subject of debate, enough is known to show that the convection currents take two quite different modes. One of these breaks the strong lithosphere; the other moves surface fragments and plates about.It is pointed out that if expanding mid-ocean ridges move continents and plates, geometrical considerations demand that the expanding ridges must themselves migrate. Hence, collisions between ridges and plates are likely to have occurred often during geological time.Twenty years ago it was shown that the effect of a "mid-ocean ridge in the mouth of the Gulf of Aden" was to enter and rift the continent. This paper points out some of the conditions under which such collisions occur and in particular shows that the angle of incidence between a ridge and a coastline has important consequences upon the result. Several past and present cases are used to illustrate that collisions at right angles tend to produce rifting; collisions at oblique angles appear to terminate in the lithosphere in coastal shears, creating displaced terrane, but in the mantle the upward flow may continue to uplift the lithosphere far inland and produce important surface effects; collisions between coasts and mid-ocean ridges parallel to them produce hot uplifts moving inland. For a time these upwellings push thrusts and folds ahead of them, but they appear to die down before reaching cratons.

Evwie (Kola Nut) and its socio-religious values among Idjerhe people of Nigeria PEOPLE OF NIGERIA

2021 ◽  
Vol 42 (1) ◽  
pp. 51-63
Author(s):  
Peter O. O. Ottuh ◽  
Keyword(s):  
West Africa ◽  
Critical Review ◽  
Religious Values ◽  
Mutual Trust ◽  
Religious Activities ◽  
Edible Fruit ◽  
The Earth ◽  
The People ◽  
The Subject ◽  
Participatory Observation

The popular edible fruit called kola nut that is found all over the Earth is native to the people of West Africa. In Idjerhe (Jesse) culture, the kola nut is part of the people’s traditional religious activities and spirituality. The presentation, breaking, and eating of the kola nut signifies hospitality, friendship, love, mutual trust, manliness, peace, acceptance, happiness, fellowship, and communion with the gods and spirits. These socio-religious values of the kola nut among the Idjerhe people are not well documented,however, and this paper aims to fill the lacuna. It employs participatory observation and oral interviews, supported by a critical review of scholarly literature on the subject. The research posits that churches can use the kola nut as a Eucharistic element that would be meaningful and indigenous to the Idjerhe people.

Project rAn:  Games to promote awareness of natural disasters in young students

2021 ◽  
Author(s):  
Jose Saraiva ◽  
Priscila Doran ◽  
Rosa Doran
Keyword(s):  
Natural Disasters ◽  
Natural Disaster ◽  
Serious Game ◽  
Early Age ◽  
Human Settlements ◽  
Complex Interactions ◽  
The Earth ◽  
The Subject ◽  
Young Students

<p>The Earth is an amazing planet. However, it is also an unpredictable and wild one – part of its many charms. Atmosphere, hydrosphere, geosphere are alive, and can unleash awesome forces on the whole planet, including the biosphere, of which we humans are part. It’s important to make young students aware of the fact that we all live in a planet that was not made specifically for humans, and that it is absolutely imperative that our species learns to respect it and its rhythms and cycles.</p><p>Human settlements are often located in pleasant areas, with little or no concern about their vulnerability to natural disasters. Authorities, local, regional and national, should make preparations to prevent and mitigate their occurrence, of course. But at least as important is the need to create awareness in the citizens, so they can face any disaster and react in a calm and orderly way. That task must begin at an early age. Other than learning to deal with natural disasters and avoiding panic, schoolkids can exert a powerful influence in the adult members of their families and alert them to the measures they should adopt to prepare for any future occurrence.</p><p>In project rAn, EU-funded, we aim to develop a serious game, adjusted to the age of the targets, that will teach them about four types of natural disaster (earthquakes, floods, fires and storms) and make them aware of how to prepare and react in case of one of them striking their city or village. The game will be easy to play, and given the small age of the players will not feature complex interactions. It will include contributions from teachers and groups of students from all Europe, that will be challenged to create small games on the subject, using the Scratch language.    </p>

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