ALBERT

Beschreibung: Additional keywords: co-seismische hydrogeologische Phaenomene, seismotektonisches Modell

Beschreibung: The Modular Opto-electronic Multispectral Stereo Scanner MOMS-02 experimental data acquired during the German Spacelab D2 mission will be used for a broad range of geoscientific objectives. The simultaneous acquisition of high spatial resolution, multispectral and stereo scenic data enables a real combination of thematic and topographic information, thus considerably improving the verification and interpretation of dynamic changes of the Earth"s surface by means of remote sensing. This paper gives a first assessment of the MOMS-02/D2 mission, the data quality and an overview on the planned methodological and application-oriented investigations for various test sites. On the basis of a few examples the possibilities of this system for future thematic applications is shown.

Beschreibung: Additional keywords: background information, PAMERAR programme, Syrian seismic network, site selection, network configuration, network optimisation, network instrumentation, seismometer vaults, short period seismometers, strong-motion seismometers, broadband seismographs, environmental shielding, data transmission, telemetry, open questions, Hintergrund-Informationen, PAMERAR-Programme, telemetrisches seismisches Netz Syriens, Auswahl von Stationsstandorten, Konfiguration des seismischen Netzes, Optimierung des Netzes, Instrumentierung, Seismometerkeller, Umweltabschirmung, kurzperiodische Seismometer, Strong-motion-Seismometer, Breitbandseismographen, Datenuebertragung, Telemetrie, zentrale Datenerfassung, offene Fragen

Beschreibung: Additional keywords: Zirkular, Programm, Hintergrund-Informationen, Teilnehmer, Lektoren, Kursauswertung, Schlussfolgerungen, Empfehlungen, Finanzabrechnung, Workshops, nationale Abende, Nachfolgestudien, Zertifikate

Beschreibung: Additional keywords: Phasenerkennung, Entfernungsbestimmung, Azimutbestimmung, Laufzeitkurven, Laufzeittabellen, Kartenprojektion

Beschreibung: We propose a new method of petrologic modeling allowing equilibrium mineral compositions, densities, and elastic properties of rocks to be calculated from their bulk chemical compositions and pressure-temperature (P-T equilibrium conditions. To calculate the mineral composition of a rock, the method of direct minimization of the Gibbs free energy is used applying to the eight-component (SiO2 - Al2O3 - Fe2O3 - FeO - MgO - CaO - Na2O - K2O) multiphase closed thermodynamic system. The density of rock, the isotropic VP, VS, and their P-T derivatives are computed on the actual mineral compositions, with the use of available experimental data on elastic moduli of minerals. Good accuracy of the computations is supported by comparison with experiments on the phase transitions gabbro/eclogite in rocks and with high-precision laboratory measurements of elastic wave velocities in samples of magmatic and metamorphic rocks. The calculated phase diagrams are given together with isolines of density, elastic wave velocities, and their pressure and temperature derivatives for some abundant anhydrous magmatic rocks ranging from granite to lherzolite. The density and elastic wave velocities noticeably increase with formation pressure of rock due to proceeding several mineral reactions resulting in the appearance and growth of garnet and disappearance of plagioclase. Character of the pressure dependence of VP and VS is determined by the bulk chemical composition of rock and can essentially be nonlinear. Rocks of different bulk compositions are well-distinguished on the plots of VP - VP/VS density. Such diagrams together with phase diagrams can be employed as efficient means for petrological interpretation of seismic data.

Beschreibung: Additional keywords: Germany, Baden-Wuerttemberg, Swabian Alp, Lower Rhine Embayment, Saxo-Thuringian earthquake province, Central German earthquake of 1872, Vogtland, Western Bohemia swarm earthquakes, mining induced seismic events, probabilistic seismic hazard, earthquake regulations, Europaeische Plattengrenzen, Deutschland, Seismizitaet von Mitteleuropa, tektonische Einheiten, Verteilung der maximalen Horizontalspannungen, Krustendeformation, Herdmechanismen, seismische Energieausloesung, Erdbebenprovinzen, Rheingraben, Niederrheinische Bucht, Schwaebische Alb, saechsische-thueringische Erdbebenprovinz, Westboehmen, Erdbebenschwaerme, mitteldeutsches Erdbeben von 1872, probabilistische Erdbebengefaehrdung, bergbauinduzierte Ereignisse, Erdbebennormen

Beschreibung: Summary: In vertical seismic profiling tube waves are generally classified as noise. They have, however, useful applications: tube waves can be generated by compressional waves at fluid-filled cracks crossing the wall of the borehole. In this case the permeability of the fracture zone can be estimated from the amplitude ratio of the incident P wave and the generated tube wave. In the present study an improved model for tube-wave amplitude interpretation is presented. While former models assumed isolated cracks, now, the consideration of fracture zone of a certain porosity, permeability and width is allowed. Master curves are used to check the senility of the amplitude ratio of tube and P waves with respect to the formal parameters of computation. It is shown, moreover, that mainly those parts of a fracture contribute to the tube-wave generation which are within a radius of about 1 m of the borehole. The localization and characterization of fracture zones by tube waves was investigated with several complementary field experiments in shallow boreholes in crystalline rocks as vertical seismic profiling (VSP) with three-component borehole geophones and hydrophones, televiewer measurements, well tests and temperature measurements. It turned out that fracture zones were met at all depths where tube waves were generated. However, not all of them were found to be hydraulically activated during well test and temperature measurements. This means that fractures detected by tube-wave VSP are not necessarily of hydrological importance. Transmissivity values based on tube-wave analysis are, therefore, an upper limit for the well under consideration. On the other hand, the transmissivity values derived from the well tests agreed quite well with those of the tube-wave analysis if only the "open" fracture zones were considered: a fact which seems to confirm our theoretical model.

Beschreibung: Abstract: Although Central Europe is a rather stable platform area it is not void of seismic activity. It crust has mainly been consolidated and internally structured by Hercynian folding ands subsequent block-faulting in connection with the collision of Africa and Europe and the related Alpine orogeny in the south. Dominating later fault tectonic features in Germany are the Upper and Lower Rhinegraben in the west ands the Hercynian striking Franconia Line and the Central German Main faults in the centre and the east, respectively, as well as several N-NNE striking, obviously older and deeper rooted fault zones both on the Franconia platform in the southwest (the 9 degree-E zone) and in northeast Germany (12 degree-E zone). The seismic activity is related to this structural inventory and more or less concentrated in some shear-zones which are currently active under the recent orientation of the stress field in Central Europe. Focal mechanisms are chiefly horizontal strike-slip and normal faulting. Composition and heat flow controlled crustal rheology limit the focal depth to a maximum of about 22 km, normally between about 5 and 15 km. The Benioff-graphs of the various active regions in Germany show generally episodes of increased and reduced activity with different time constants and patterns hinting to different stress loading and relaxation histories and related crustal rheologies. Geodetically determined recent crustal movements, young tectonic deformations and the history of earthquake activity in Germany make it unlikely that events with magnitudes above 6 and epicentral intensities above 8.5 degree MSK will occur. The largest mining induced seismic events in Germany were almost of the same order. The paper discusses the seismic activity and its peculiarities in the main seismic regions of Germany, the unique swarm earthquakes in the Vogtland/Western Bohemia in particular. Damages incurred in connection with the strongest tectonic earthquakes in recent years, i. e. the 1978 earthquake in the Sabina Alb and the Redmond earthquake of 1992 near the German-Dutch border, are compared with that of the probably strongest mining-induced event in the history of mankind in 1989 at Voelkerhausen (M = 5.5; I max + 9 degree MSK). The current German hazard maps as derived by various authors both on the basis of probabilistic considerations and actual repeated macroseismic observations are shown and related to the seismic zoning and building regulations which are currently applied. Additional keywords: Baden-Wuerttemberg, Rheingraben, Swabian Alp, Lower Rhine Embayment, Saxo-Thuringian earthquake province, Central German earthquake of 1872, Vogtland, Western Bohemia swarm earthquakes, mining induced events, probabilistic hazard, regulations, Europaeische Plattengrenzen, Deutschland, Seismizitaet von Mitteleuropa, tektonische Einheiten, Verteilung der maximalen Horizontalspannungen, Krustendeformation, Herdmechanismen, seismische Energieausloesung, Erdbebenprovinzen, Niederrheinische Bucht, Schwaebische Alb, saechsische-thueringische Erdbebenprovinz, Westboehmen, Erdbebenschwaerme, mitteldeutsches Erdbeben von 1872, probabilistische Erdbebengefaehrdung, bergbauinduzierte Ereignisse, Erdbebennormen

Beschreibung: Summary: There exists important discrepancy in modelling earth tides on a rotating elliptical earth. The latitude dependences of Love number k_2, and the gravimetric factor delta_2, given by my model are significantly less than given in previous publications. My numerical procedure is checked by the analytical solution based on a simple homogeneous incompressible elastic model. The reliability of my numerical method, in this special case, is excellent. Adopting Dean's definition of the gravimetric factor for a spherical earth, there is no significant latitude dependence of this parameter.

Beschreibung: Earthquake hazard parameters such as maximum expected magnitude, Mmax, annual activity rate, lambda, and b value of the Gutenberg-Richter relation have been evaluated for two regions of Egypt. The applied maximum likelihood method permits the combination of both historical and instrumental data. The catalogue used covers earthquakes with magnitude ≥ 3 from the time interval 320-1987. The first area, Gulf of Suez, has higher seismicity level than the second, all other active zones in Egypt. b-values of 1.2 ± 0.1 and 1.0 ± 0.1 are obtained for the two areas, respectively. The number of annually expected earthquakes with magnitude ≥ 3 is much larger in the Gulf of Suez, 39 ± 2 than in the other areas, 6.1 ± 0.5. The maximum expected magnitude is calculated to be 6.5 ± 0.4 for a time span of 209 years for the Gulf of Suez and 6.1 ± 0.3 for a time span of 1667 years for the remaining active areas in Egypt. Respective periods of 10 and 20 years were reported for earthquakes of magnitude 5.0 for the two subareas. -from Authors