High magnitude global seismicity and lateral velocity gradients

Summary A new significant correlation has been sought between high magnitude global seismicity and lateral surface wave velocity gradients. Rayleigh wave velocity divisioning of Eurasia, Africa, Pacific Ocean, Atlantic Ocean and Indian Ocean into regions of similar group velocity dispersion character of 30 sec period bySanto andSato [1]³) has been mainly used for calculating the gradients. It is quite striking to note that all earthquakes of magnitude 8.6 and above during 1897–1956 have occurred in regions having gradients of the order of 1.5·10^–3 sec^–1.Finally, some potential areas for high magnitude earthquake occurrences are predicted and the possible velocity gradients in regions, where division pattern is not yet investigated like South America and Australia, are also estimated.N.G.R.I. Contribution No. 70-170.     

The viscous damping of internal waves on the rotating earth

Summary A formula is derived for the spatial attenuation of the two possible modes of oscilation of a two-layer, rotating system. If the long-wave approximation is made, it is found with reference to the internal mode that this formula disagrees with an earlier result obtained byRattray [8]²).     

A new measure of seismicity

Summary In this paper an attempt has been made to analyse the World shallow focus earth-quakes by the method ofGutenberg andRichter. Frequency-magnitude analysis of various earthquakes indicate that in the relation logN=a–b M, the ratio (b/a)^–1 satisfies fairly well the seismicity of a region and it is felt that this ratio may be used as a measure of seismicity for a given region.     

The earthquake of Carnuntum in the fourth century a.d. – archaeological results, seismologic scenario and seismotectonic implications for the Vienna Basin fault, Austria

Excavations in the former Roman provincial capital of Pannonia Superior, Carnuntum, 40 km east of Vienna revealed damaged masonry structures from many parts of the ancient settlements. A compilation of structurally damaged buildings has formerly been given by Kandler (Acta Archaeol Acad Sci Hung, 41:313–336, 1989), who related damage to an earthquake in the middle of the fourth century a.d. This paper reviews and supplements these data, and discusses the significance of the style of damage. It is concluded that seismic damage is the only likely interpretation for the damaging mechanism. Although archaeological age dating for the individual collapsed buildings only constrains the timing of their destruction to a few decades around 350 a.d., we assume a single damaging event. In spite of the restrictions on damage assessment by the nature of the archaeological data, it is possible to give a reasonable appraisal of macroseismic intensity. The tentative seismological interpretation of damage leads to an intensity estimate of about nine of the European macroseismic scale (EMS-1998). Comparison with macroseismic data of modern earthquakes in the region, which show a rapid decrease of intensity with distance form the epicentre, indicate a near-by seismic source unless exceptionally high epicentral intensities are assumed for the fourth century event. The most likely source is an active sinistral strike-slip fault (Lassee Fault) passing about 8 km NW of the archaeological site. The fault belongs to Vienna Basin fault system with about 2 mm sinistral movement per year. The system is characterized by fault segmentation and distinct seismicity along the different segments. Moderate seismicity during the last centuries at the southern segments (e.g., Schwadorf 1927, I ₀=8) strongly contrasts from the Lassee fault segment with Carnuntum as the only known severe earthquake. The earthquake of Carnuntum provides evidence for the overall seismic style of deformation along this segment, which previously has not been regarded seismically active. Also, the fourth century earthquake is the strongest event known from the Vienna Basin fault so far.     

Rayleigh wave propagation in a two-layer anisotropic media

Summary The possibility of propagation of Rayleigh waves in an incompressible crust of constant density and rigidity varying exponentially with depth lying on a semi-infinite transversely isotropic base has been discussed in this paper. Frequency equation has been derived and numerical calculations are made. The result obtained in this case is compared with that ofNewlands [3]²) andDutta [4].     

Die äquatoriale Beschleunigung bei Sonne,Jupiter und Saturn nebst Betrachtungen über die Form der Kontinente

Zusammenfassung Ausgehend von derEmden'schen Theorie der äquatorialen Beschleunigung der Sonne und einer früheren Anwendung derselben auf den Planeten Jupiter, wird auch die Beschleunigung bei Saturn hier erstmalig diskutiert und der Versuch gemacht, dieselbe Theorie zur Erklärung der Ostabweichung der Kontinente der Erde im äquatorialen Gebiet anzuwenden. Das ist nur möglich, wenn man 1.) auf die archaische Periode der Erdentwicklung zurückgreift, bei der aber die wesentlichen Höhenunterschiede der Erdoberfläche schon ausgebildet waren, 2.) der Pol im wesentlichen die jetzige Lage hatte und 3.) der Reibungskoeffizient der festen Erdkruste aber wesentlich geringer war: 10¹⁴ gegen etwa 10²⁰ c.g.s.

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Summary The hypothesis ofR. Emden to explain the equatorial acceleration of the sun has newly been discussed by the author and 11 years ago applied to the rotation ot the planet Jupiter. It is possible to apply her also to the planet Saturn and to the earth in the archaic period of evolution. The earth shows a striking eastern curvature of the continents in the equatorial zone, which possibly has originatet in times, when the earth crust was capable to yield to the same forces, which drive the equatorial zone forwards in rotating gaseous and liquid spheres, as the sun and the great planets. It is nenessary to suppose an invariable position of the pole and the principal height differences of the crust already developed. It is found, that the viscosity of the earth in that time has been small in comparison to its present value (10¹⁴ to 10²⁰ c.g.s.).

     

Eruptive history of Karymsky volcano,Kamchatka, USSR,based on tephra stratigraphy and 14C dating

Eruptions of the active Karymsky stratovolcano began about 5300 (6100 ¹⁴C) b.p. from within a pre-existing caldera which formed 7700 ¹⁴C b.p. As indicated by 32 ¹⁴C determinations on buried soils and charcoal, the volcano has gone through two major cycles of activity, separated by a 2300 year period of repose. The first cycle can be divided into two stages (6100–5100 and 4300–2800 b.p.). The earlier stage began with especially intense eruptions of basaltic andesite to dacite. The later stage was characterized by moderate-strength eruptions of andesite. The second cycle, which is characterized by weak to moderate intermittent eruptions of andesite, started 500 b.p. and continues to the present. Eruptive patterns suggest that this cycle may continue for at least another 200 years with an eruptive character similar to that of the recent past.     

An investigation of the size frequency resolution of an aerosol by the static method of diffusion

Summary Theoretical considerations are put forward for identifying the Dynamic and Static Methods of Diffusion measurements of aerosol particles. On the basic of this equality the Exhaustion Method of Diffusion developed byPollak andMetnieks for the size-frequency resolution of a heterogeneous aerosol by Dynamic Diffusion Methods should be applicable to Static Methods. This hypothesis is tested using a Pollak-Nolan nucleus counter as decay vessel. It is shown that turbulence in the counter is the most serious obstacle against this type of approach to finding the size components of an aerosol. The time involved, the high humidity in the counter and a hypothetical nucleus-free zone are other major difficulties for relatively large Aitken nuclei. It is established, however, that for particles whose diffusion coefficient is of the order of 10^–3 cm² sec^–1, the proposed method should be quite workable.     

The thermal diffusivity of red sandy soil at Waltair

Summary The study of heat exchanges or temperature changes in the surface layers of the soil are important in agricultural science at tropical latitudes. The quantity, thermal diffusivity largely determines the temperature change produced in any layer of the soil when heat is conducted there from an adjacent layer. Therefore, the authors have determined the thermal diffusivity of the soil from range and lag methods suggested byJohnson andDavies [15]²) andCoutis [7] respectively. The values of diffusivity cbtained from these methods agree well with each other. The effect of soil moisture on diffusivity has been studied. The diffusivity increases with the increase of moisture in the surface layers of the scil. The ratio of ranges of soil temperature at different depths is found to be approximately constant which is in agreement with the theory of heat flow into the soils. The results of diffusivity obtained from these methods agree well with those results of past workers. The mean value of the thermal diffusivity of red sandy soil at the experimental site of Waltair is found to be 6.336×10^–3 cm²/sec.     

On the evaluation of planetary albedo of the earth from turbidity measurements in India

Summary The planetary albedo of the earth has been evaluated from the turbidity measurements in India by usingÅngström's empirical relation [1]²) and the same has been presented in this paper. The diurnal and seasonal variations of the planetary albedo have been discussed. It has been found that during the morning hours, albedo is usually more than that during afternoon hours. Further, it shows a minima during winter season and a maxima during hot summer months.     

A fluid-filled fracture as possible mechanism of ground deformation at Phlegraean Fields,Italy

Two uplift episodes have recently been recorded at Phlegraean Fields, a volcanic region near Naples (south-central Italy). The first episode occurred in 1970 and lasted up to 1972; the second has begun at the end of 1982 and is still in progress.An attempt to model the ground deformations which occurred during the 1970–1972 event is made in this paper. The source has been assumed to be a two-dimensional fluid-filled fracture, similar to a sill. A good fit with experimental data has been obtained for a short (1–2 km long) shallow (3 km deep) source and a driving pressure ranging from 60 to 210 bars. Rigidity values have been fixed at 3.5–4.0 × 10¹⁰ c.g.s., with Poisson ratio equal to 0.3.This solution which differs from previous approaches byMogi (1958) andWalsh andDecker (1971) is non-unique, but the present results are in good agreement with observed horizontal and vertical displacements. Notwithstanding the oversimplification made in assuming a homogeneous elastic semi-infinite medium, the predicted stress field seems to be in agreement with the fault-plane solutions and the pattern of epicenters determined for the uplift-seismic swarm episode that is still in progress.     

A determination of the wind-driven ocean circulation from the vorticity budget of the atmosphere

Summary The annual mean distribution of the surface stress curl over the Northern Hemisphere has been estimated from the horizontal vorticity advection in the atmosphere by using the upper-wind statistics as published byCrutcher [2]³). The results are used to compute the wind-driven mass transport (Sverdrup transport) in North Atlantic and North Pacific. The calculated intensity of the Gulf Stream is largest at the latitude 35°N, where a mass transport of 45×10⁶ tons sec^–1 is obtained; for the maximum intensity of the Kuroshio current a value of 60×10⁶ tons sec^–1 is obtained.Research supported in part by the Section of Atmospheric Sciences, National Science Foundation, Grant GP-2561.The research for this study was started by the author at the Department of Meteorology and Oceanography, The University of Michigan, Ann Arbor, Mich.     

Vertikale und zeitliche Verteilung der Leitfähigkeit in einem eutrophen Gewässer während der Sommerstagnation

Summary Data are given of the vertical distribution of temperature, conductivity and alkalinity of an eutrophic lake (Rotsee near Lucerne) measured at short intervals during the summer stratification. We were able to prove in a limited measure only the expected day's periodicity from the conductivity of the CO₂-assimilation of the phytoplankton. We found pronounced internal ‘seiches’ in the hypolimnion; their mathematical interpretation is given only in the order of size.Rodhe's diagram andNümann's method make it possible to determine quantitative relations; from the chemical point of view the lake (depth 16,5 m) shows a four-layered type during the summer.      

Possibility of ground observations of electron spin-flip radiation from lowerE-region electrons

Summary Landovitz & Marshall (¹) have suggested a maserlike mechanism to explain the decameter emission from the Jovian ionosphere. Although the application of the suggested mechanism for emission outwards into space from our planet is obvious, it is our purpose to show that if this mechanism is indeed operative, emission of electron spin-flip radiation from the electrons in the lower part of theE-region is also possible. An order of magnitude estimate predicts that thisE-region radiation which travels downward can be observed by ground receivers.     

A new ultrasonic interferometer for the determination of equation of state parameters of sub-millimeter single crystals

A new giga-Hertz ultrasonic interferometer has been developed, based on ultrasonic microscopy technology. The interferometer operates from 0.3 GHz to 1.5 GHz. The high frequency and associated small wavelengths together with the large bandwidth make it possible to measure travel times in samples with thicknesses of several microns and allow for unprecedented accuracy in bond corrections. An absolute accuracy of 1 part in 10⁵ in travel time measurements is achievable in single crystals (thickness of 200 microns) or glasses of interest to the earth sciences. The high precision travel time data, combining with sample length measurements using a laser interferometer built in our laboratory, yield very high precision ultrasonic velocities.The interferometer is intended for use in conjunction with a newly developed 4 GPa gas piston cylinder apparatus (Getting andSpetzler, 1993) for equation of state measurements under simultaneous pressure and temperature. A separate correction for the bond will be made for each datum at every point in temperature pressure space.     

On the propagation of spherical waves due to large underground explosion

Summary When a high explosive pressure acts on the boundary of a spherical cavity in an elastic medium, the material in a region around the charge behaves plastically and thereafter an elastic wave is propagated. Not only that but the elastic plastic boundary moves also with a certain velocity which is less than the elastic wave velocitySabodash [3]²). In this paper, firstly the case when the elastic plastic boundary moves with a velocityV ₀. (V ₀<c) has been dealth with. The pressure in the elastic medium on this boundary has been assumed to be constant and equal toP ₀. Secondly the case when the elastic plastic boundary moves with an exponentially decaying velocity has been considered. The pressure in the elastic medium on this boundary has also been assumed to be of exponential character.     

Flow past spheres and spheroids in the presence of a toroidal magnetic field

Summary Stewartson [1]²) has considered the inviscid flow past a sphere in the presence of a uniform magnetic field andMurray andLudford [2] have investigated a similar problem in which the magnetic field originates from an axially symmetric dipole field situated at the centre of the sphere. In connection with the study of earth's magnetic field, the toroidal part of this field plays a dominant part. This gives rise to the importance of studying the effect of a toroidal magnetic field on flows past different bodies of revolution; specially past spheres and spheroids. In the present note inviscid flows past a sphere, and a spheroid, are considered, for the case of a toroidal magnetic field originating in the fluid. In the case of the sphere the field inside the sphere consists of an electric dipole directed along the axis of symmetry together with a uniform electric field which produces a uniform current along the axis. In the case of the spheroid, the field inside it is due to an electric dipole and quadrupole directed along the axis of symmetry, together with a uniform electric field which produces a uniform current along this axis.     

Partial melting models for the petrogenesis of Reykjanes Peninsula basalts,Iceland Implications for the use of trace elements and strontium and neodymium isotope ratios to record inhomogeneities in the upper mantle

The mixing of magmas derived from two major compositional layers in a vertically stratified mantle has been favoured by Zindler et al. [1] in their interpretation of the REE and Sr and Nd isotope data for basalts from the Reykjanes Peninsula. However, a model involving the dynamic partial melting of a regionally homogeneous, veined mantle can also explain the major and trace element data and be reconciled with an alternative interpretation of the time relationships of the lavas to that presented by Jakobsson et al. [2]. Moreover, it is possible to explain the constant⁸⁷Sr/⁸⁶Sr but variable¹⁴³Nd/¹⁴⁴Nd ratios of the lavas by this model if the vein and wall rock components of the mantle source have equilibrated for Sr but not for Nd isotopes — a state that has been interpreted for some veined mantle nodules [13]. The model presented also involves more realistic degrees of partial melting than the alternative magma mixing models and satisfactorily explains the erupted volumes of the different magma types found in the area. Interpreting the basalt geochemistry in these terms suggests that Sr isotope ratios of the lavas monitor different scales of heterogeneity in the precursor mantle sources than Nd isotope ratios.     

Caractérisation hydrogéochimique de la nappe du Continental Intercalaire (sud tunisien) / Hydrogeochemical characterization of the Continental Intercalaire aquifer (southern Tunisia)

Abstract

The study of the Continental Intercalaire aquifer system of southern Tunisia, based on the interpretation of geochemical (major elements) and isotopic (¹⁸O, ²H, ¹³C and ¹⁴C) data, has aided the understanding of the hydrodynamics of this multi-layer aquifer system, which is greatly influenced by tectonics. The determination of the origin of groundwater salinization and the understanding of the hydrogeological and geochemical behaviour of this aquifer were achieved by studying the correlation between the major elements and total mineralization (TDS). By using isotopic tools, it was shown that the water of this aquifer has been recharged under cooler, palaeoclimatic conditions. The technique also made it possible to better understand the hydrodynamic functioning of the aquifer system: it showed that the relatively recent recharge of the aquifer has been by direct infiltration from carbonate and sandy outcrops of the Cretaceous and Miocene, respectively, located in the eastern and northeastern parts of the aquifer. The ¹⁸O content was used to calculate the altitude of recharge basins. The isotopic gradient defined in this study is ?0.5 δ¹⁸O ‰/100 m.     

Directional permeability of porous media to homogeneous fluids

Summary Investigations have shown that in groundwater- and oil-bearing strata there are preferential directions of flow that are often maintained over wide areas.Johnson & Hughes (1948, see Ref.) analysed a series of oil well cores by cutting them into small horizontal plugs and they obtained directional permeabilities which they plotted in the form of polar graphs. They were not able to give a physical explanation of this phenomenon. On the other hand, there exists a theory of permeability in which the latter is represented as a symmetric tensor. This theory has been developed byFerrandon (1948, see Ref.), but no experimental substantiation of it seems ever to have been attempted.In the present paper, the author undertakes to compare the two sets of findings. FromFerrandon's theory, the directional permeabilities (denoted byk) corresponding to the experiments ofJohnson & Hughes are calculated and it is shown thatk ^–1/2 if plotted as polar graph, should form an ellipse. The data ofJohnson & Hughes are then are drawn. In this manner, a substantiation of the tensor theory ofFerrandon is obtained.

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Zusammenfassung Untersuchungen der Permeabilität von Grundwasser und Erdöl führenden Gesteinsschichten haben gezeigt, dass dieselbe in vielen Fällen richtungsabhängig ist. Hierbei bleibt die Richtung extremaler Permeabilität oft über weite Gebiete konstant.Johnson & Hughes untersuchten eine Reihe von Bohrkernen von Oelquellen auf Richtungsabhängigkeit der Permeabilität. Hierzu schnitten sie aus denselben kleine, waagrechte Stücke, bestimmten deren Permeabilität und stellten das Ergebnis ihrer Messungen in der Form von Permeabilitätspolardiagrammen dar. Sie waren nicht im Stande, eine theoretische Erklärung der erhaltenen Kurven zu geben. Auf der anderen Seite existiert eine Theorie der Permeabilität, wobei die letztere als symmetrischer Tensor behandelt wird. Diese Theorie wurde vonFerrandon vorgeschlagen; es scheint aber, dass keine experimentelle Bestätigung davon je versucht worden ist.In der vorliegenden Arbeit vergleicht der Verfasser die zwei Typen von Untersuchungen. Nach derFerrandon'schen Theorie wird die «gerichtete» Permeabilität (mitk bezeichnet), die den Experimenten vonJohnson & Hughes entspricht, berechnet. Es wird gezeigt, dassk ^–1/2, als Polardiagramm dargestellt, die Gestalt einer Ellipse haben sollte. Die Resultate vonJohnson & Hughes werden dann in die Form vonk ^–1/2 umgerechnet und als entsprechende Polardiagramme dargestellt. In dieser Weise wird eine experimentelle Bestätigung der Tensortheorie vonFerrandon erhalten.

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Published by Permission of Imperial Oil Limited, Calgary, Alberta (Canada).