ALBERT

Description: The permanent rotation of the N.E.Pacific Rift is divided into three first-order rotations covering the whole rift between 20° and 60° N. during the last 80 mio years. The general movement of a clockwise rotation (35-40° altogether) was interrupted during the time between 40 and 20 m.y.b.p. by a weak counterclockwise one (8° altogether). These superordinate rotations can be subdivided in smaller ones with an average duration of 10 m.y. only. It is to suppose that all these rotations are a readjustment of the rift to a changed position of the spreading pole. Compared to it, short-time, oscillatory rotations represent compensating movements of the rift and stabilizing efforts of the plate. For the S.E.Pacific Rift it is supposed that the. Counterclockwise rotation taking place there for the last 7 m.y. is continuing, as may be concluded from the distribution of earthquake epicentres. Furthermore, the problems of pendulum movements and hinge zones at the S.E. and N.E.Pacific Rifts are discussed, which represent the magmatic activity of the rift. Hinge zones are lines of weakness of rifts, which can become fault zones. Up to now they were not mentioned in literature. The internal deformations of the Pacific Plate and Juan de Fuca Plate off California indicated by kinks of the rift, fault-folding and strike slip faults became intense about 1-2 m.y.b.p.

Description: 1. Introduction 2. Superordinate rotations of the East Pacific Rift between 20° and 60° N. 2.1. The clockwise rotation of the N.E. Pacific Rift 80 m.y.b.p. (1st period) 2.2. The counterclockwise rotation of the N.E. Pacific Rift :from 71 to 63 m.y.b.p. (2nd period) 2.3. Rotations of the rift during a transitional stage about 65 to 60 m.y.b.p. (3rd period) 2.4. The great clockwise rotation of the N.E. Pacific Rift 63 to 50 m.y.b.p. (4th period) 2.5. Rotations with a stabilizing function in a transitional stage from 50 to 40 m.y.b.p. (5th period) 2.6. The great counterclockwise rotation of the N.E. Pacific Rift 43 to 20 m.y.b.p. (6th period) 3. Total rotation of the East Pacific Rift between Clarion and Aja Fracture Zones 3.1. Sum of rotations of the rift 3.2. Special position of the plate section between 33° and 37° N. 3.3. The significance of the Mendocino-Pioneer double structure 4. Rotations of the Pacific-Antarctic Rift between 30° and 65° s. 4.1. Complex movements of the rift 4.2. Recent tendencies 5. Magmatic activity of the rift 5.1. Characteristics of rift activity 5.2. Hinge zones of the rift rotations 6. Plate deformation 6.1. Rift rotation at a collision of plates 6.2. Rift shortening due to compression 7. Conclusions References

Description: The tables and graphs result from evaluation of Model 1 (see Veröffentlichungen des Zentralinstituts für Physik der Erde, Nr. 41, Potsdam 1976). They help to approximate values of the hydrostatic pressure P, the bulk modulus and its pressure derivative and the seismic parameter of a sample at any volume contraction x in the range between 0.5 and 1 if these quantities referred to the initial state (P = 0) are known. The considered functions are tabulated for a set of grid points of the rectangle 0.5 ≤ x ≤ 1, 2.1 ≤ ϰ_1 ≤ 10, where ϰ_1 is the initial value of the pressure derivative of the bulk modulus. The lattice pitchs are 0.01 in x and 0.1 in ϰ_1. The inverse problem can also be solved approximately with the aid of the tables and, above all, the plots presented here by using the "method of corresponding curves".

Description: Summary 1. Preface 2. Theoretical excursus 3. Some remarks on Model 1 4. Instructions for using tables and plots 5. References 6. Tables and figures

Description: This 3rd International Symposium "Geodesy and Physics of the Earth" was according to its tenor the continuation of the Symposia of 1970 and 1973 dealing with the same basic topic. It was especially devoted to the possibilities of Satellite Geodesy to study geodynamic processes. By this also those problems of the use of observations of artificial satellites for geodetic and geophysical purposes were dealt with that had regularly been treated in the preceding years and will be treated further by A. Massevitsch in the symposia presided by her. Several papers were devoted especially to the problems of the Special Study Group 5.49 of the International Association of Geodesy "Use of Geodetic Data for Studies of Earth-Moon-System" (President E. Tengström). Part 2 : Global and Planetary Dynamics of the Earth

Description: Evaluation of numerous data from different methods of measurement and theories applied in high-pressure physics shows that the strain energy of a monophase system, which represents the low- or a high-pressure phase of a hydrostatically compressed substance mostly relevant to planetary physics, approximates to a term proportional to the square of an auxiliary function of the volumetric contraction, the bulk modulus and its successive partial derivatives with respect to pressure at the initial state of the thermodynamical system. From this it follows that new-defined polynomial equations in the initial values of the bulk modulus and its pressure derivatives must be satisfied, which is checked for many elements, halides, oxides, minerals, and rocks. Using a suitably chosen auxiliary function, the strain energy, pressure, bulk modulus and its first pressure derivative at any equilibrium state of the monophase system are represented by approximation functions of the volumetric contraction as well as the initial values of the bulk modulus and its derivatives. The information content of these functional relations called Model N if they include derivatives of the bulk modulus only up to the order N surpasses, already in the cases N = 1 end N = 2, that of other relations hitherto used for interpreting the compressional behaviour of different substances. Model 1 is discussed on the base of more than 70 substances with various compressional properties, among them stishovite and solid hydrogene, proved to be suitable, in particular, for the physics of the interiors of the Earth and of terrestrial planets. Considering the reliability of the data material available, Model 1 is pointed out to predict experimental values from the tested substances for volumetric contractions down to about 0.5 with a relative error between 1 % and 5 %. Model 2, extending the information volume of Model 1, turns out to be appropriate for volumetric contractions less than 0.5 as is the case in the interiors of the Jovian planets. For practical use of both models tables and graphs of sensitivities and errors of significant quantities are presented. In case data from shock-wave experiments on rocks and minerals are available, Model 1 is used for identification of crystal structures of high-pressure phases. As a result, for the majority of high-pressure phases the compressional behaviour differs from that of the corresponding oxide mixtures. For some substances new conclusions on their crystal structures can be drawn.

Description: 1. Introduction 2. Basic relations 3. Approximations for the equation of state 4. The conditions of the auxiliary variable 5. Development of Model 1 and Model 2 6. Practical analysis of the models 6. 1. Preliminaries 6.2. The parameters "0 and "1 6.3. Intercomparison of different forms of the equation of state 6.4. The parameter n2 6.5. Problems of accuracy 6.6. Discussion of [x,P]-data of elements 6.7. Discussion of [x,P]-data of halides 6.8. Discussion of [x,P]-data of oxides, minerals, and rocks 6.9. On the "interpolating equations of state" 7. Conclusion 8. Tables and Figures References