Magmatismes basiques dits “orogeniques” et “anorogeniques” et teneurs entro2: Les associations “Isotitanees” et “anisotitanfes”

The patterns of variation of TiO₂ conent during magmatic evolution are different in the so called “orogenic” and “anorogenie” basic associations; these last terms, which are the cause of much misunderstanding, can be replaced by the terms “isotitaniferous” and “anisotitaniferous”.     

The “wave turbopause”

The “wave turbopause” is defined as the mesospheric altitude level where the temperature fluctuation field indicates a substantial increase in wave amplitudes in the vertical direction.The turbopause altitude is analyzed on the basis of four years of SABER data (2002–2005, Version 1.06). Substantial seasonal and latitudinal variations are found, with some interannual variability also present. Seasonal changes are annual at high latitudes, semi-annual at low latitudes, and a mixture of both at middle latitudes. Southern hemisphere data are similar as in the North if shifted by half a year. Latitudinal variations show a minimum in the tropics and two relative maxima at middle latitudes.The “wave turbopause” is found near to zero-wind lines or low-wind zones (zonal wind). It is compared to rocket and other measurements, and interesting similarities are obtained. The wave turbopause can also be found in the HAMMONIA GCM. A preliminary analysis shows results similar to those of the SABER measurements.     

NEW FILTERING METHODS WITH “VIBROSEIS”*

In order to obtain high resolution correlograms, it is of importance amongst other things to get reflection signals with large bandwidth. An advantage of the VIBROSEIS *** *** Trade Mark and Service book of the Continental Oil Company.
method is that the frequencies radiated by the vibrators can be matched to the transmission response of the subsurface involved. By choosing the right frequency range, the highest possible amplitude and most favourable form may be given to the reflection signals. In a reflection correlogram, individual signals cannot be considered in isolation. Signals of different origin are interfering with one another. They very often have different amplitudes, so that it may be desirable in many cases to filter out events of certain apparent velocity. With the VIBROSEIS method this may be achieved quite simply. All frequencies of the noise signal are uniformly suppressed. The advantage is that noise signals, e.g. refraction signals, which cannot be sufficiently attenuated by wavelength filtering, may be completely eliminated by this velocity filtering without affecting the bandwith of the desired signal. The total dynamic range of the tape recording can be used for the registration of wanted events. To perform this kind of filtering several vibrators are necessary in the field; each of them is controlled by an individual signal. There is an unavoidable error of static and dynamic corrections which causes the results of reflection measurements to deteriorate when using multiple coverage. High frequency components especially are seriously affected by destructive interference. This difficulty can be avoided by using a VIBROSEIS signal with high frequency component amplitudes supported. For the probability of error of corrections a normal distribution is assumed. A smoothed amplitude characteristic may be achieved after stacking. The amplitude characteristic of seismic devices is commonly reduced to about 100 cps bandwidth. For further improvement of resolution of VIBROSEIS correlograms it is necessary to apply special filtering methods. This is of particular interest when any kind of gain control is used to display weak events more clearly. With increasing amplification the sidelobes of the strong signals may reach the size of the weak events. In order to eliminate this effect, the amplitude characteristic of the VIBROSEIS signal is adjusted for optimum suppression of side-lobes.     

NEW FILTERING METHODS WITH “VIBROSEIS”*

In order to obtain high resolution correlograms, it is of importance amongst other things to get reflection signals with large bandwidth. An advantage of the VIBROSEIS *** *** Trade Mark and Service book of the Continental Oil Company.
method is that the frequencies radiated by the vibrators can be matched to the transmission response of the subsurface involved. By choosing the right frequency range, the highest possible amplitude and most favourable form may be given to the reflection signals. In a reflection correlogram, individual signals cannot be considered in isolation. Signals of different origin are interfering with one another. They very often have different amplitudes, so that it may be desirable in many cases to filter out events of certain apparent velocity. With the VIBROSEIS method this may be achieved quite simply. All frequencies of the noise signal are uniformly suppressed. The advantage is that noise signals, e.g. refraction signals, which cannot be sufficiently attenuated by wavelength filtering, may be completely eliminated by this velocity filtering without affecting the bandwith of the desired signal. The total dynamic range of the tape recording can be used for the registration of wanted events. To perform this kind of filtering several vibrators are necessary in the field; each of them is controlled by an individual signal. There is an unavoidable error of static and dynamic corrections which causes the results of reflection measurements to deteriorate when using multiple coverage. High frequency components especially are seriously affected by destructive interference. This difficulty can be avoided by using a VIBROSEIS signal with high frequency component amplitudes supported. For the probability of error of corrections a normal distribution is assumed. A smoothed amplitude characteristic may be achieved after stacking. The amplitude characteristic of seismic devices is commonly reduced to about 100 cps bandwidth. For further improvement of resolution of VIBROSEIS correlograms it is necessary to apply special filtering methods. This is of particular interest when any kind of gain control is used to display weak events more clearly. With increasing amplification the sidelobes of the strong signals may reach the size of the weak events. In order to eliminate this effect, the amplitude characteristic of the VIBROSEIS signal is adjusted for optimum suppression of side-lobes.     

HOW TO WRITE FOR “GEOPHYSICAL PROSPECTING”*

The acceptance of articles in Geophysical Prospecting is strictly based on the originality and relevance of the contents. In order to be published a paper has to satisfy additional requirements on its external form and on its style and language: it should be written preferably in English though articles in French and German are permitted. A paper should consist of (i) a title page, (ii) an abstract, (iii) the text, (iv) list of references, (v) captions to illustrations, if any, (vi) tables, if any, and (vii) illustrations, if any. These seven parts should be mailed together but be physically separable and should be prepared according to rules which are either based on printing necessities or on the editorial style of the Journal. Failure to comply with these rules may result in delay in further processing of the article. Since Geophysical Prospecting is edited with a minimal budget correspondence with authors is kept to a minimum.     

“Site & region-specific” response spectra: a probabilistic approach

Design seismic forces depend on Peak Ground Acceleration (PGA) values and on the shape of Response Spectrum (RS) curves dictated by Building Codes or which need to be evaluated in every particular case. The PGA values and RS curves strictly depend on earthquake magnitude and distance, as well as on the regional and local geological conditions. At present, there is no doubt that it is necessary to construct so-called “Site & Region-specific” Building Code provisions reflecting the influence of different magnitude events at different distances that may occur during the life time of the construction, as well as the variety of local ground conditions. A scheme of Uniform Hazard Response Spectra and PGA estimation considering local site response is described in this paper. The assessments of these design parameters are obtained on the basis of Uniform Hazard Fourier spectra using the conception of “dominant earthquakes”. The effect of local geology is included by means of the soil/reference site spectral ratios.     

Zur Ansprache des “Verkrautungszustandes” in Fließgewässern

Vorgestellt wird ein einfaches Verfahren zur schnellen und gleichzeitig differenzierten Ansprache des Vcrkrautungszustandes von Fließgewässern für Zwecke der wasserwirtschaftlichen Praxis sowie zur ökologischen Beurteilung des Gewässers. Das Verfahren beruht auf der getrennten Bestimmung von Verkrautungsform und Verkrautungsgrad mit Hilfe eines Schlüssels, wobei die Verkrautungsform eine Synthese aus ökologischen und hydraulischen Einheiten darstellt. Die häufigsten Verkrautungsformen werden anhand von Bildern, die Anwendung anhand von Beispielen dargestellt.