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101.
Frequency analysis of the Sumatra-Andaman earthquake of 2004, one of the most significant and best-recorded earthquakes, is
based on spectral seismograms obtained from their broadband seismograms. The Sumatra-Andaman earthquake is found to have a
wide-range frequency content of P-wave radiation during the rupturing process. On the basis of stacking spectral seismograms
we distinguished four time events of the rupturing process of a total length of about 540 s. The frequency, f
max, is the highest for the first event (0.163 Hz in time interval 0–88 s), lowest for the second — which is the strongest (0.075
Hz in time interval 88–204 s). For third and fourth events frequencies are similar (0.089 and 0.082 Hz in time intervals 204–452
and 452–537 s, respectively). The frequency also shows an azimuthal dependence (±0.02 Hz). Azimuths for which the frequency,
f
max, has maximum and minimum values are 203–222° and 23–42°, respectively. These observations are discussed in relation to previously
published papers on this topic. 相似文献
102.
Laser-Ablation-Inductive-Coupled-Plasma Mass Spectrometry (LA-ICP-MS) has proved to be a reliable tool to date metatorbernite–bassetite solid solution series in Pleistocene weathering pits developing on the surface of Late Variscan granites. The maximum age of weathering in these granites in NW Spain is 1.61 ± 0.01 Ma. The likelihood to find uranyl phosphates or silicates amenable to LA-ICP-MS dating increases with increasing silica content in the magmatic bedrocks (granites) and with decreasing grade during regional metamorphism (low-grade-stage/greenschist metamorphics) of the parent material. Uranyl vanadates may be used for geochronological studies during the Quaternary as well but they are confined to arid morphoclimatic zones. 相似文献
103.
Water and Iron effect on the P-T-x coordinates of the 410-km discontinuity in the Earth upper mantle
Fiorenza Deon Monika Koch-Müller Dieter Rhede Richard Wirth 《Contributions to Mineralogy and Petrology》2011,161(4):653-666
We performed multi-anvil experiments in the system MgO-SiO2 ± H2O at 13.0–13.7 GPa and 1,025–1,300°C and in the system MgO-FeO-SiO2 ± H2O, under reducing conditions, at 11.0–12.7 GPa and 1,200°C, to depict the effect of H2O on the P-T-x coordinates of the 410-km discontinuity, i.e. the olivine–wadsleyite phase boundary. The charges were investigated
with Electron Microprobe (EMP), Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Secondary Ion Mass Spectrometry
(SIMS) and Electron Energy Loss Spectroscopy (EELS). We observe in the MgO-SiO2-H2O system at 1,200°C a 0.6 GPa shift of the phase boundary to lower pressure compared to dry conditions, due to the stronger
water fractionation into wadsleyite (wad) rather than in olivine (ol). In the MgO-FeO-SiO2-H2O system, we reproduced the triple point, i.e. observed coexisting hydrous ol, wad and ringwoodite (ring). SIMS H quantifications
provided partitioning coefficients for water:
D\textwad/ol\textwater D_{\text{wad/ol}}^{\text{water}} ~ 3.7(5) and
D\textring/ol\textwater D_{\text{ring/ol}}^{\text{water}} ~ 1.5(2) and
D\textwad/ring\textwater D_{\text{wad/ring}}^{\text{water}} ~ 2.5(5). For a bulk composition of x
Fe = 0.1, our data indicate only a slight difference in the width of the loop of the two phase field ol–wad under hydrous conditions
compared to dry conditions, i.e. no broadening with respect to composition but a shift to lower pressures. For bulk compositions
of x
Fe > 0.2, i.e. in regions where wad–ring and ol–ring coexist, we observe, however, an unexpected broadening of the loops with
a shift to higher iron contents. In total, the stability field of hydrous wad expands in both directions, to lower and higher
pressures. Fe3+ concentrations as determined by EELS are very low and are expected to play no role in the broadening of the loops. 相似文献
104.
Marcin Polkowski Beata Plesiewicz Jan Wiszniowski Monika Wilde-Piórko Passeq Working Group 《Acta Geophysica》2016,64(6):2092-2113
PASSEQ 2006–2008 (Passive Seismic Experiment in TESZ; Wilde-Piórko et al. 2008) was the biggest passive seismic experiment carried out so far in the area of Central Europe (Poland, Germany, the Czech Republic and Lithuania). 196 seismic stations (including 49 broadband seismometers) worked simultaneously for over two years. During the experiment, multiple types of data recorders and seismometers were used, making the analysis more complex and time consuming. The dataset was unified and repaired to start the detection of local seismic events. Two different approaches for detection were applied for stations located in Poland. The first one used standard STA/LTA triggers (Carl Johnson’s STA/LTA algorithm) and grid search to classify and locate the events. The result was manually verified. The second approach used Real Time Recurrent Network (RTRN) detection (Wiszniowski et al. 2014). Both methods gave similar results, showing four previously unknown seismic events located in the Gulf of Gdańsk area, situated in the southern Baltic Sea. In this paper we discuss both detection methods with their pros and cons (accuracy, efficiency, manual work required, scalability). We also show details of all detected and previously unknown events in the discussed area. 相似文献
105.
Monika B. Kalinowska Paweł M. Rowiński Janusz Kubrak Dorota Mirosław-Świątek 《Acta Geophysica》2012,60(1):214-231
The problem of two-dimensional mathematical modelling of heated cooling water discharges into running waters is considered
in the paper. Two models — one for the evaluation of 2D turbulent velocity field and the other, developed by authors of the
study, for 2D heat transport in open-channels — were used in the calculations. Relevant scenarios of the spread of heated
water discharged from a designed gas-stem power plant to be constructed at the Vistula River were presented. Environmentally
most friendly variant of the discharge of the thermal pollution was selected from among four various variants. 相似文献
106.
Monika Breitzke Olaf Boebel Saad El Naggar Wilfried Jokat Berthold Werner 《Geophysical Journal International》2008,174(2):505-524
Air guns and air-gun arrays of different volumes are used for scientific seismic surveys with R/V Polarstern in polar regions. To assess the potential risk of these research activities on marine mammal populations, knowledge of the sound pressure field of the seismic sources is essential. Therefore, a broad-band (0–80 kHz) calibration study was conducted at the Heggernes Acoustic Range, Norway. A GI (2.4 l), a G (8.5 l) and a Bolt gun (32.8 l) were deployed as single sources, 3 GI (7.4 l), 3 G (25.6 l) and 8 VLF™ Prakla-Seismos air guns (24.0 l) as arrays. Each configuration was fired along a line of 3–4 km length running between two hydrophone chains with receivers in 35, 100, 198 and 263 m depth. Peak-to-peak, zero-to-peak, rms and sound exposure levels (SEL) were analysed as functions of range. They show the typical dipole-like directivity of marine seismic sources with amplitude cancellation close to the sea surface, higher amplitudes in greater depths, and sound pressure levels which continuously decrease with range. Levels recorded during the approach are lower than during the departure indicating a shadowing effect of Polarsterns's hull. Backcalculated zero-to-peak source levels range from 224–240 dB re 1 μPa @ 1 m. Spectral source levels are highest below 100 Hz and amount to 182–194 dB re 1 μPa Hz–1 . They drop off continuously with range and frequency. At 1 kHz they are ∼30 dB, at 80 kHz ∼60 dB lower than the peak level. Above 1 kHz amplitude spectra are dominated by Polarstern's self-noise. From the rms and sound exposure levels of the deepest hydrophone radii for different thresholds are derived. For a 180 dB rms-level threshold radii maximally vary between 200 and 600 m, for a 186 dB SEL threshold between 50 and 300 m. 相似文献
107.
Rüdiger Glaser Dirk Riemann Johannes Schönbein Mariano Barriendos Rudolf Brázdil Chiara Bertolin Dario Camuffo Mathias Deutsch Petr Dobrovolný Aryan van Engelen Silvia Enzi Monika Halíčková Sebastian J. Koenig Oldřich Kotyza Danuta Limanówka Jarmila Macková Mirca Sghedoni Brice Martin Iso Himmelsbach 《Climatic change》2010,101(1-2):235-256
The paper presents a qualitative and quantitative analysis of flood variability and forcing of major European rivers since AD 1500. We compile and investigate flood reconstructions which are based on documentary evidence for twelve Central European rivers and for eight Mediterranean rivers. Flood variability and underlying climatological causes are reconstructed by using hermeneutic approaches including critical source analysis and by applying a semi-quantitative classification scheme. The paper describes the driving climatic causes, seasonality and variability of observed flood events within the different river catchments covering the European mainland. Historical flood data are presented and recent research in the field of historical flood reconstructions is highlighted. Additionally, the character of the different flood series is discussed. A comparison of the historical flood seasonality in relation to modern distribution is given and aspects of the spatial coherence are presented. The comparative analysis points to the fact that the number of flood events is predominately triggered by regional climatic forcing, with at most only minor influence on neighbouring catchments. The only exceptions are extreme, supra-regional climatic events and conditions such as anomalous cold winters, similar to that of 1784, which affected large parts of Europe and triggered flood events in several catchments as a result of ice-break at the beginning of the annual thaw. Four periods of increased occurrence of flooding, mostly affecting Central European Rivers, have been identified; 1540–1600, 1640–1700, 1730–1790, 1790–1840. The reconstruction, compilation and analysis of European-wide flood data over the last five centuries reveal the complexity of the underlying climatological causes and the high variability of flood events in temporal and spatial dimension. 相似文献
108.
The Schmidt‐Teleskop‐Kamera (STK) is a new CCD‐imager, which is operated since begin of 2009 at the University Observatory Jena. This article describes the main characteristics of the new camera. The properties of the STK detector, the astrometry and image quality of the STK, as well as its detection limits at the 0.9 m telescope of the University Observatory Jena are presented (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
109.
Temperature and precipitation fluctuations in the Czech Republic during the period of instrumental measurements 总被引:2,自引:0,他引:2
Rudolf Brázdil Pavel Zahradní?ek Petr Pi?oft Petr ?těpánek Monika Bělínová Petr Dobrovolny 《Theoretical and Applied Climatology》2012,110(1-2):17-34
The history of early meteorological observations using instruments in the Czech Lands is described (the longest temperature series for Prague-Klementinum starts in 1775, precipitation series for Brno in 1803). Using the PRODIGE method, long-term monthly temperature and precipitation series from selected secular stations were homogenised (for 10 and 12 stations, respectively). All the seasonal and annual temperature series for the common period 1882–2010 show a significant positive linear trend with accelerated warming from the 1970s onwards. No significant linear trends were disclosed in the series of seasonal and annual precipitation totals. Correlation coefficients between the Czech series analysed decrease as distances between measuring stations increase. A sharper decrease of correlations for precipitation totals displays much weaker spatial relationships than those for mean temperatures. The highest correlations between all stations appeared in 1921–1950, the lowest in 1891–1920 (temperature) and 1981–2010 (precipitation). Wavelet analysis reveals that very distinct annual cycles as well as the slightly weaker semi-annual ones are better expressed for temperature series than for precipitation. Statistically significant cycles longer than 1?year are temporally unstable and sporadic for precipitation, while in the temperature series cycles of 7.4–7.7 and 17.9–18.4?years were recorded as significant by all stations in 1882–2010 (quasi-biennial cycle of 2.1–2.2?years for half the stations). Czech homogenous temperature series correlate best with those of the Northern Hemisphere for annual, spring and summer values (with significant correlation coefficients between 0.60 and 0.70), but this relation is temporally unstable. Circulation indices, such as the North Atlantic Oscillation Index (NAOI) and the Central European Zonal Index (CEZI), may explain the greater part of Czech temperature variability, especially from December to March and for the winter; however, this relationship is much weaker, or even random, for precipitation series. Further, relationships with the Southern Oscillation Index (SOI) are weak and random. Relatively weak coincidences exist between statistically significant cycles in the Czech series and those detected in NAOI, CEZI and SOI series. 相似文献
110.