Morphotectonics of the Lake Albert Rift Valley and its significance for continental margins

The Lake Albert region is described as an example of a rift valley. It is far more complex than the typical graben used by rift valley modellers. The northern section is a complex half graben with en echelon faults and warps on the west. The central section is a graben, but with uplift axes remote from the faults. The southern section is complicated by the partly faulted but mainly upwarped tilt block of the Ruwenzori massif. Many features of the landscape—drainage patterns, erosion surfaces, regolith—pre-date the rift valley tectonics, and provide insight into the dating and evolution of tectonic features. As rift valleys are precursors of seafloor spreading, the rift geomorphology shows which features may pre-date the formation of new continental edges. Many modern passive margins have morphotectonic features that date back to the rift valley stage of crustal evolution.     

On disturbances in a visco-elastic medium of Maxwell type in contact with a liquid medium and subjected to a magnetic field

Summary The problem of disturbances in a visco-elastic medium due to Maxwell in contact with a liquid medium — both being perfectly conductive — has been investigated when an impulsive force acts along the plane of the contact. The electro-magnetic equations of Maxwell, equation of elasticity and the stress-strain relations of the material have been used in the investigation.     

Das Erdstrom-Observatorium bei Nagycenk (Ungarn)

Zusammenfassung Im ersten Teil des Artikels werden — nach einem kurzen geschichtlichen Rückblick — die Anlage und die technischen Einrichtungen des im IGJ bei Nagycenk (Ungarn) errichteten tellurischen Observatoriums dargelegt. Der zweite Teil beschäftigt sich mit der Bearbeitung der Registrierungen. Wir wollen in erster Richtung die Verteilung der Variationen von verschiedenen Perioden untersuchen, und wir ordneten deshalb, teils auf Grund der Gegebenheiten der Registrierungen, hauptsächlich aber der Untersuchung bei verschiedenen Typen wegen, die Variationen in 5, bzw.9 Klassen ein. Ausserdem führen wir die tellurischen Äquivalenten der magnetischen Phenomena (Bay, Sturm, usw) und die Grundlagen deren Einteilung an. Die Publikationen über Karakteristiken und Graphikons zweccks Erkennung der Eigenschaften der Variationen werden wir von Zeit zu Zeit forsetzen.

---

Summary In the first part of the article the writers — after a brief historical note — acquaint with the question of the location of the telluric observatory, established during the IGY near Nagycenk (Hungary) and with its technical arrangements. The second part presents the preparation of the records. It was chiefly the distribution of the different periodic variations in our mind, and this is why we included the variations, partly based on the given conditions of the recording, but in first line on the examination of periods of the different types in 5, respectively in 9 classes. Moreover, we specify the telluric equivalents of magnetic phenomena (bay, storm, etc.) and the basic principles of the classification. We shall report periodically on the characterics and graphs concerning the feature of the variations.

     

Trends in athens temperature

Summary Temperature records of a long period (1858–1952) for Athens, in the form of overlapping 30-year intervals, are analyzed with a view to be investigated temperature trends.While the winter temperature has been rising almost continously during the period under consideration, the increase of summer temperature — to which the annual temperature and the annual temperature range as well are rather similar — has occured altogether during the second half of the record. During the first half the summer and annual temperatures and the annual range were all decreasing. The oceanicity increased during the first half and decreased during the second.The total change has been a rise of 0.90 deg. in winter temperature, a fall of 0.7 followed by a rise of 1.00 deg. in summer temperature, and a fall of 0.3 then a rise of 0.70 deg. in annual temperature.The rapid increase of population and also variations in solar activity seem to have partly influenced the Athens temperature trends.Presented at the tenth General Assembly of the International Union of Geodesy and Geophysics in Rome (Italy), September 1954.     

Perturbations of the upper atmosphere in the cleft region

In the dayside polar region—loosely referred to as the cleft region—particle precipitation and Joule heating cause significant perturbations of the upper atmosphere. Here Dynamics Explorer-2 satellite data are used to present a synopsis of these disturbance effects. Documented are an increase in electron temperature and a decrease in electron density; increases in ion drift speed and ion temperature; an increase in the upward-directed ion velocity; increases in zonal wind speed and neutral gas temperature; and changes in the neutral gas composition and mass density. It is suggested that the increase in electron temperature is partly controlled by the decrease in electron density; that the ion upflow velocity mainly depends on the electron temperature, less frequently on the ion temperature; and that the observed decrease in thermospheric mass density is due to a decrease in the atomic oxygen density, which in turn is caused by diverging wind flows.     

Field pond as a sink for nutrients migrating from agrocenoses to freshwaters

Nutrients migrating from agrocenoses through drainage effluents are retained in a field pond. Studies were carried out concerning the effectiveness of this process in an aquatic environment in the conditions of development of phytoplankton and submersed and floating-leaved macrophytes (1987), in the state of phytoplankton dominance (1988), and, in a swamp environment, in the state of dominance of emergent macrophytes (1991).The greatest effectiveness of this process was found in the conditions of development of aquatic plants, i.e. submersed and folating-leaved macrophytes and phytoplankton. In the warm season of 1987 the retention of nutrients (in g · m^–2) was: TN — 7.20, TP — 3.5, K — 3.80, Ca — 119, and Mg — 8.2. When the euglenoid phytoplankton dominated, the level of retention was slightly higher and the export of N_org was also noted (3.27 g · m^–2 season^–1). In the case of dominance of emergent macrophytes, a reduction in the TN load, particularly in N-NO₃ (by 3.67 m^–2 season^–1), occurred, though at the same time a release of P, K, and Mg was noted. The export exceeded the import of TP by 0.44, K by 15.3, and Mg by 1.4 g · m^–1. The conditions for the functioning of a field pond as a sink for nutrients migrating from agroecosystems to surface waters were determined.     

A gigantic Bezymianny-type event at the beginning of modern volcan Popocatepetl

The history of volcan Popocatepetl can be divided into two main periods: the formation of a large primitive volcano — approximatively 30 km wide — on which is superimposed a modern cone (6–8 km in diameter and 1700m high). A major event of Bezymianny type marks the transition between these two dissimilar periods.The activity of the primitive volcano was essentially effusive and lasted several hundred thousands of years. The total volume of products ejected by the volcano is of the order of 500–600 km³. Its last differentiated magmas are dacitic.A gigantic debris flow (D.F.) spread on the southern side is related to the Bezymianny-type event which destroyed the summit area of the ancient edifice. An elliptical caldera ( 6.5 × 11 km wide) was formed by the landslide. Its deposits, with a typical hummocky surface, cover 300 km² for a volume of 28–30 km³. Numerous outcrops belonging to this debris flow show “slabs” of more or less fractured and dislocated rocks that come from the primitive volcano. These deposits are compared to two studied debris flows of similar extent and volume: the Mount Shasta and Colima's D.F.This eruption takes a major place in the volcanologic and magmatic history of Popocatepetl: pyroclastic products of surge-type with “laminites” and crude layers, ashflows, and pumiceous airfall layers are directly related to this event and begin the history of the modern volcano probably less than 50,000 years ago. In addition, a second andesitic and dacitic phase rose both from the central vent — forming the basis of modern Popo — and from lateral vents.The terminal cone is characterized by long periods of construction by lava flows alternating with phases of destruction, the duration of these episodes being 1000 to 2000 years. The cone is composed of two edifices: the first, volcan El Fraile, began with effusive activity and was partly destroyed by three periods of intense explosive activity. The first period occurred prior to 10.000 years B.P., the second from 10.000 to 8000 years B.P. and the third from 5000 to 3800 years B.P. Each period of destruction shows cycles producing collapsing pyroclastic flows or nuées of the St Vincent-type related to the opening of large craters, plinian air-fall deposits and minor lava flows. The second edifice, the summit Popo, produced lava flows until 1200 years B.P. and since that time, entered into an explosive period. Two cataclysmic episodes, each including major pyroclastic eruptions, occurred 1200 and 900–1000 years ago. During the Pre-Hispanic and historic times effusive activity was restricted entirely to the summit area alternating with plinian eruptions. Nevertheless, despite the quiet appearance of the volcano, the last period of pyroclastic activity which started 1200 years ago may not have ended and can be very dangerous for the nearby populations.     

Dynamic response of pile groups with different configurations

A general methodology is outlined for a complete seismic soil—pile-foundation—structure interaction analysis. A Beam-on-Dynamic-Winkler-Foundation (BDWF) simplified model and a Green's-function-based rigorous method are utilized in determining the dynamic response of single piles and pile groups. The simplified model is validated through comparisons with the rigorous method. A comprehensive parameter study is then performed on the effect of pile group configuration on the dynamic impedances of pile foundations. Insight is gained into the nature of dynamic pile—soil—pile interaction. The results presented herein may be used in practice as a guide in obtaining the dynamic stiffness and damping of foundations with a large number of piles.     

On the radioactivity of summer clouds on Mount Olympus

Summary The radioactivity in different parts of a cloud as well as the radioactivity of the atmosphere before and after the cloud's passage are examined with stationary samplers — fall-out pans, Grunow cloud-catchers of various materials, and air-pumps — at elevations of 1800 m and 2817 m, on Mt Olympus — Greece. The relation between the cloud's density and its radioactivity is also examined.     

On the deformations in a general linear substance of a layered media subjected to a body force and a deforming magnetic field

Summary The propagation of disturbances has been studied in a layered media, comprising a liquid and a general linear substance, subject to a body force and permeated by an initial magnetic field acting normal to the plane of the contact. The effect of the body force due to some internal source has been considered in the problem and a set of results has been obtained under two possible extreme variants of the boundary conditions in the form of integral forms, which can be computed to visualize the displacement—time and displacement—depth variations, both in the presence and absence of the body force. The effect of body force on the substance has been, as a sample case, illustrated in the graphs. The stress-strain relation of the general linear substance and the electromagnetic equations of Maxwell have been used in working out the problem.     

Heat flow anomalies caused by water circulation

The practically important part of geothermal systems belongs to the convective type where the thermal energy is transported by movement of water or steam. Both geothermics and hydrology should be in very close cooperation at the interpretation of convective geothermal anomalies.In the first part of the study the parameters required for the calculation of water- and thermal-balance will be enumerated and their obtainable accuracy will be discussed based mainly on the praxis used in Hungary.In the second part, heat convection problems connected to subterranean water movement will be discussed, divided into three cases which have importance in praxis:

• — regional water-flow systems with great inflow and outflow areas;

• — mountainous — mainly karstic — areas of infiltration with springs at the foot of the mountain;

• — closed convective systems of circulation.

For illustrating the conceptual examples given above, Hungarian case histories with characteristic data will be presented: The Transdanubian Middle Range, Spa of Budapest, Spa of Héviz, the Great Hungarian Plain and the Thermal Anomaly at Tiszakécske.     

Damping characteristics of gravity waves obliquely incident on a monomolecular film: Part II

Calculations of viscous damping chracteristics of gravity waves, propagating obliquely across finite monomolecular films, are represented graphically to demonstrate the influence of angle of incidence, film edges, and surfactant properties. It is found that regions of negative damping may occur, particularly towards the rear of extensible slicks. For wide slicks, both the amplitude and the domain of significant edge effects on the local damping coefficient decrease with angle of incidence. Multiple-slick systems can damp waves more effectively—with appropriate choice of surface-active material—than an equivalent single slick.     

Rockburst induced ground motion—a comparative study

While rockbursts from underground copper mining in Western Poland normally produce surface peak ground accelerations (PGA) and velocities of 0.05–0.1 g and 1–3 cm/s, occasionally these peak motions may exceed 0.15 g and 10 cm/s, respectively. These larger motions are of considerable concern and an investigation has been undertaken to define the nature of these larger induced ground motions. This paper compares these rockburst motions with low intensity earthquakes. Various strong motion parameters such as PGA, peak ground velocity (PGV) and displacements as well as strong motion duration, Arias intensity, Fourier and response spectra are compared with those from earthquakes. It is concluded that although short duration is the most obvious parameter that differentiates rockbursts from earthquakes, in fact their high dominant frequencies, which result in high PGA/PGV ratios differentiate them the most. Two types of rockburst-induced ground motions are indicated in this paper: typical—with 3–6 months return period and characteristic, high frequency content—as well as rare events similar to shallow, low intensity earthquakes.     

Versuch einer Analyse der gemittelten vertikalen Ozonverteilung in verschiedenen geographischen Breiten

Zusammenfassung Aus den bei Ballonaufstiegen, bei Mondfinsternissen und durch den Umkehreffekt gemessenen Ozonverteilungen werden für verschiedene geographische Breiten gemittelte Ozonverteilungen abgeleitet und mit den theoretisch photochemisch berechneten Verteilungen verglichen, wodurch der Spielraum der letzten erheblich eingeengt wird. — Die Diskrepanz zwischen der berechneten und der gemessenen Ozonverteilung unterhalb des Ozonmaximums in 23 km Höhe lässt auf eine bedeutende Wirkung des Massenaustausches in der Troposphäre und in der unteren Stratosphäre schliessen, der nach den Aequator hin stark zunimmt. — In mittleren und höheren Breiten tritt — vornehmlich im Frühjahr — ein zweites tieferes Ozonmaximum in 16 km Höhe auf, das photochemisch nicht zu erklären ist, sondern advektiv, durch aus polaren Breiten herzugeführtes Ozon bedingt wird.

---

Summary The mean ozone distribution for various geographical latitudes is derived from ozone distributions measured by means of balloon ascents, eclipses of the moon and the «Umkehreffekt» and compared with the theoretically calculated photochemical distributions, whereby the full scope of the latter is considerably limited. —The discrepancy between the calculated and the measured ozone distribution below the ozone maximum at 23 km altitude is a sign of a considerable effect of mass exchange in the troposphere and lower stratosphere which increases towards the equator. In the mean and higher latitudes we find — especially in spring — a second lower ozone maximum at 16 km altitude which cannot be explained photochemically but is probably due to advection, to ozone transported down from polar latitudes.

     

Some laboratory experiments with a rotating,differentially heated fluid annulus

Summary With a view to modelling more realistically certain large-scale meteorological and oceanographic flows, some experiments are described in which temperature and velocity fields are measured in a rotating, differentially heated fluid annulus, and their dependence upon the imposed boundary conditions is investigated. It is demonstrated that with suitable construction of the annulus walls the strength of the zonal baroclinic motion may be chosen independently of the basic density stratification. Most of the measurements described are for the symmetric flow regime. In the experiments it is found that certain aspects of the observed temperature and flow fields — in particular the basic stratification and the slope of the isotherms — agree reasonably well with theoretical estimates.     

Niederschlags- und Ladungsbildung im Gewitter

Zusammenfassung Die Vorstellungen über die Elektrizitätsbildung in den Gewitterwolken erlauben die Annahme, dass diese Elektrizitätsbildung ein Mass für die in den Wolken vorhandene Gesamt-Niederschlagsmenge liefern kann. Zur überprüfung dessen werden die Ladungsbildungen — charakterisiert durch die Häufigkeit der Entladungen - und die Gesamt-Niederschlagsmenge — gemessen durch den Zufluss zu einer Talsperre — miteinander korreliert. Der erichen diese für eine quantitative Verknüpfung noch nicht aus. Zur besseren Niederschlagserfassung sind Radarbeobachtungen in Aussicht genommen.

---

Summary The conceptions on the formation of electricity in thunderclouds permit to accept that the formation of electricity may provide a measure for the entire amount of precipitation existing in the clouds. In order to examine this idea the formation of charge — characterized by the number of discharges - and the total amount of precipitation — given by the flowing in to a barrage — are correlated with each other. The relationship expected following from the results so far obtained exists for the present only in a qualitative manner because the measurement of the total amount of precipitation by means of a barrage is too inexact. For a better registration of the precipitation amount radar-observations are planned.

     

Analytical solutions for flow to a well through a fault

We present explicit analytical solutions to problems of steady groundwater flow to a pumping well in an aquifer divided by an infinite, linear fault. The transmissivity of the aquifer is allowed to jump from one side of the fault to the other to model the juxtaposition of host rocks with different hydrologic properties caused by faulting. The fault itself is represented as a thin anisotropic inhomogeneity; this allows the fault to act as a combined conduit–barrier to groundwater flow, as is commonly described in the literature. We show that the properties of the fault may be represented exactly by two lumped parameters—fault resistance and fault conductance—and that the effects of the fault on flow in the adjacent aquifer is independent of the fault width. We consider the limiting cases of a purely leaky and a purely conductive fault where the fault domain may be replaced exactly by internal boundary conditions, and we investigate the effects of fault properties on the flow behavior in the adjacent aquifers. We demonstrate that inferring fault properties based on field observations of head in the aquifer is inherently difficult, even when the fault may be described by one of the two limiting cases. In particular, the effects of a leaky fault and a conductive fault on heads and discharges in the aquifer opposite the fault from the well, are shown to be identical in some cases.     

Optimal annual operation of a water supply and distribution system

A model for determining the optimal operation of Israel's National Water System over 1 year, with monthly time increments, is described. The water system contains the Main National Carrier — some 250 km long from the Kinneret (Sea of Galillee) in the north to the Negev region in the south — and some 25 regional water systems connected to it. Water is taken from the Kinneret and from two aquifers. Water transfers may take place between the National Carrier and regional systems, and between interconnected regional systems.The mathematical model of the system represents its monthly production and transfer capacities. Given the monthly demands which have to be met and the hydraulic constraints the model determines the month-by-month operating plan which minimizes energy costs over the year.The optimization model is formulated as a linear program. This necessitates several types of approximations and linearizations, which are discussed in detail. The optimal operating plan for 1977–78 is compared with the actual operation of that year and conclusions are drawn from the comparison concerning the practicality and adequacy of the model's output and the potential for effective operation and for energy savings.     

Expansion of a Plane Wave into Gaussian Beams

Magnetic susceptibility measurements on topsoils have often been used during the last few years to detect anthropogenic pollution. In most cases, a Bartington susceptibility meter for field measurements was used. However, up to now, no standard procedure has been developed for carrying out such investigations. The purpose of our study was to test the compatibility of different set-ups of instruments used for this purpose and the possible influences of subjective (human) factors. Field magnetic susceptibility measurements, carried out with four different Bartington MS2D instruments in strictly defined positions, are very consistent both for low and high values. The correlation coefficient between the magnetic susceptibility values recorded with different Bartington MS2D probes reached 97–98%. A test area was mapped independently by two groups, without any restrictions concerning the choice and distribution of the measured points, but respecting a few standard conditions (e.g., measuring at a distance from tree trunks; on the flattest place possible; recording between 10–30 values per point). The resulting susceptibility maps show the same general features in both cases, suggesting that the measuring strategy applied is suitable for topsoil magnetic screening. The methodology proposed can be used to map magnetic susceptibility on a larger scale—for example Europe—providing large sets of representative data and eliminating border-transition biases and human errors.     

Active tectonics of the Northern Apennines and Adria geodynamics: new data and a discussion

The active geodynamic setting of the Northern Apennines is characterised by extension in the axial zone of the chain, and by a more complex tectonic behaviour in the frontal part of the belt. In the latter sector, moderate seismicity occurs, displaying compressional, strike-slip and extensional focal plane solutions with variably oriented P and T axes. For this area, a review of available geological and geophysical data has been integrated by the analysis of seismic reflection lines calibrated with deep well logs. This study confirms that, as already suggested by some previous workers, thrusting and related folding in the study area ceased in Early Pleistocene times. This feature is in contrast with the hypothesis of active thrusting related to a subducting lithospheric slab beneath the chain—an issue which is largely debated based on available geophysical information. Our analysis shows that the Northern Apennines are characterised by an active tectonic setting which is similar to that of the central and southern portions of the belt. These areas all display a Late Quaternary inactivity of the thrust front. NE–SW oriented extension (perpendicular to the strike of the orogen) is well established in their axial zones, whereas a less homogeneous stress field characterises their external sectors and the adjacent foreland. Within this framework, the seismotectonic behaviour of the Northern Apennines—and probably of the whole Italian peninsula between the Po Plain and the Southern Apennines (north of the Calabrian Arc)—may be interpreted as essentially controlled by two main processes. The first of them involves tectonic uplift, possibly related with slab detachment and associated unbending of the foreland plate. The second process consists of a present-day northwestward motion of the Adria block with respect to stable Europe.