Pure and Applied Geophysics

Ledersteger, K.

doi: 10.1007/BF01992646pmid: N/A

Es wird eine allgemeine Theorie der mehrparametrigen Gleichgewichtsfiguren entwickelt. Die Gleichgewichtsbedingung wird folgendermaßen formuliert: 1. Das Dichtegesetz ist streng individuell. 2. Jede Gleichgewichtsfigur besteht aus mehreren, durch Diskontinuitätsflächen getrennten Teilen, deren jeder das Dichtegesetz der einparametrigen Gleichgewichtsfiguren aufweist oder homogen ist. 3. Bei Entblätterung der Figur bis zur innersten Diskontinuitätsfläche resultiert ein null oder einparametriger Kern. Für das Normalsphäroid der Erde wird ein dreiteiliges Modell zugrundegelegt, bestehend aus einer homogenen Wasserhülle, einem heterogenen Mantel und einem ebensolchen Kern. Nach Abhebung des Ozeans verbleibt eine vierparametrige Festerde, wobei die Kernoberfläche in 2900 km Tiefe angenommen wird. Da zur eindeutigen Lösung zwei Bestimmungsstücke fehlen, erhält man ∞2 Lösungen, deren Gültigkeitsbereich durch drei lineare Reihen von Grenzfiguren abgeschlossen ist: eine Figurenreihe mit homogenem Kern und heterogenem Mantel, eine Reihe mit homogenem Mantel und heterogenem Kern und eine Reihe mit verschwindendem Dichtesprung an der Kernoberfläche. Die drei Ecken des Feldes sind durch folgende Figuren gegeben:a) einWiechert'sches Modell, bestehend aus einem homogenen Mantel und einem homogen Kern; diese Figur weist das maximale HauptträgheitsmomentC auf.b) die GrenzfigurB mit homogenem Kern und verschwindendem Dichtesprung, welche das minimale Trägheitsmoment hat.c) die GrenzfigurC mit homogenem Mantel und dem Dichtesprung Null. Innerhalb der empirischen Unsicherheit fällt das aus der dynamischen und statischen Abplattung der wirklichen Erde für die Festerde berechnete Hauptträgheitsmoment mit dem Minimalwert der FigurB zusammen. Es scheint demnach, daß die wirkliche Erde durch einen minimalen Drehimpuls ausgezeichnet ist, womit aber gleichzeitig der Kern homogen sein muß und an der Kernoberfläche kein Dichtesprung auftreten dürfte.

Paul, M.

doi: 10.1007/BF01992647pmid: N/A

It is well known that the problem of determination of subsurface masses from gravity observations does not offer any unique solution. Yet, as has been shown in this paper, under some simplified but realistic assumptions some parameters of the subterrainean body are uniquely determinable in terms of some weighted double summations of gravity values (residuals). Physical significances of these parameters are also discussed. They themselves suggest about the possible mass distribution, more over they can be utilised in «cut and try method» of the determining masses.

Mal, A.

doi: 10.1007/BF01992648pmid: N/A

Generally Love-wave is absent in the corresponding spectrum of the phase in the low period range when the path tranversed is oceanic. ButOliver, Ewing & Press were able to observe this phase in seismograms of volcanic islands like Honolulu, Bermuda and others. Here, it has been attempted to explain why these waves could be recorded at volcanic stations and not elsewhere. It has been supposed that the lava settles down to form a transversely isotropic layer. Green's Function technique has been adopted to solve the problem of propagation of Love-waves through a crust whose thickness gradually decreases towards the ocean.

Wiese, H.

doi: 10.1007/BF01992649pmid: N/A

Die magneto-tellurischen Verhältnisse in Niemegk und Ückermünde wurden für einen Periodenbereich von 10 bzw. 50 sec bis 86 400 sec ausgewertet. Der scheinbare Widerstand ist abhängig von der Richtung und von der Periode. Aus den magnetischen Variationen läßt sich angenähert die Richtung der Induktionsströme bei inhomogenem Untergrund feststellen. Durch Vergleich mit Ergebnissen an anderen Orten zeigt sich, daß der elektrische Widerstand der Kruste und des Mantels in horizontaler Richtung sehr unterschiedlich ist. Die Widerstände sind kleiner als man bisher angenommen hat und keinesfalls in der Größe von 10 000 Ωm.

Båth, Markus; Tryggvason, Eysteinn

doi: 10.1007/BF01992650pmid: N/A

In August 1955 a series of specially arranged quarry blasts in the Kiruna iron ore mines was recorded with a refraction apparatus at approx. 10 km distance. The experiments are the first seismic investigations of the deeper crustal structure in Fennoscandia and were mainly undertaken in order to study near-vertical reflections from crustal discontinuities. The records show clear directP waves with sharp onsets and a velocity of 5.65±0.13 km/sec (in porphyry), furthermoreS waves of less definite onsets and sound waves through the atmosphere.P waves reflected from crustal discontinuities are weak and of erratic occurrence, in agreement with theoretical expectation for near-vertical reflections. Approx. depths to the Conrad and the Mohoroviči'c discontinuities are calculated as 19 km and 33–34 km. There is general agreement with the explosion records written by the Grenet seismograph at Kiruna, and the differences which exist can be explained by the different frequency response of the two instruments.

Båth, Markus; Tryggvason, Eysteinn

doi: 10.1007/BF01992651pmid: N/A

Records of underwater explosions in Iceland in 1959 and 1960, mainly performed for crustal studies, have been investigated with regard to amplitudes. The amplitudes ofP2 in the 1959 explosions and of the first arrivingP waves in the 1960 explosions were found to be proportional to the first power of the charge weight, whereas amplitudes ofP1 andS1 in the 1959 explosions were proportional to the 3/4-power of the charge up to 200 kg, but increased much slower for larger charges. The influence of water depth of shot point on the charge weights, required to obtain a certain amplitude, has been determined and it was found that the logarithm of the charge weight has a linear relation to water depth down to about 8 meters. The amplitudes of first arrivingP waves decrease as the inverse 2.2-power of the distance up to about 30 km. For greater distances an exponential decrease of the form (const./Δ) exp (−βΔ) is valid. ForP2 waves with a frequency of 10 cps we found β=0.027±0.003 km−1 for a profile across central Iceland and β=0.009±0.004 km−1 for a profile in the western part of Iceland.

Lisitzin, Eugénie

doi: 10.1007/BF01992652pmid: N/A

The paper deals with the slope of the sea surface in the Baltic. Chapter 1 gives a survey of the mean annual slope. In Chapter 2 are presented a few cases corresponding to the maximal observed height differences in sea level for south winds, on the one and, and north winds, on the other hand. The shares of the effect of air pressure, a progressive wave and the pilling-up of water due to the pressure of the wind force upon the water surface are estimated.

Ichiye, Takashi

doi: 10.1007/BF01992653pmid: N/A

Meridional cross sections of temperature, salinity and oxygen of the North Pacific Ocean are prepared to show location of the intermediate water, which is formed at the polar front and spreads on constantsigma-t surfaces. Geostrophic flow in a meridional plane is obtained by dynamic calculation. Friction-driven meridional circulation is determined from the zonally averaged density distribution. The latter flow seems to be more appropriate for explanation of mechanism of spread of the water.

Belluigi, Arnaldo

doi: 10.1007/BF01992654pmid: N/A

L'A. ha qui escogitato una equivalenza bisol-monosol, realizzabile sul terreno, per instaurare «elettrodiaframmi», «elettroparatie» a qualsiasi distanza dagli iniettori di legante. Ne studia gli aspetti fenomenologici principali, corredandoli di grafici utili all'impiego del metodo.

Anastassiades, Michael; Ilias, Demetrius; Tsagakis, Emmanuel

doi: 10.1007/BF01992655pmid: N/A

On November 1960 a special solar activity occured, producing characteristic disturbances in the ionosphere. Athens center followed this activity by vertical sounding and by Riometer recordings. They are evidences for proton events producing deep absorption in the ionosphere and aurora extending till 38° latitude. Some observations concerning July 1961 solar activity are reported. World wide decrease of the maximum electron density reported during the November period was observed also in Athens. Ionospheric disturbances following vertical sounding observations are of «negative» type.