Volcanic Tremor at Mt. Etna, Italy, Preceding and Accompanying the Eruption of July – August, 2001     

S. Falsaperla  S. Alparone  S. D'Amico  G. Di Grazia  F. Ferrari  H. Langer  T. Sgroi  S. Spampinato 《Pure and Applied Geophysics》2005,162(12):2583

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Use of solution-mined caverns in salt for oil and gas storage and toxic waste disposal in Germany   总被引：3，自引：0，他引：3  

M. Langer 《Engineering Geology》1993,35(3-4):183-190

The need for storage caverns for oil and gas, and repositories for toxic chemical waste is increasing world-wide. Rock salt formations are particularly suitable for the construction of cavities for such purposes. Owing to its favourable geomechanical properties, rock salt remains stable over long periods of time without support, and it can be shown that the geological barrier of the host rock remains intact for a remarkably long time.

Safety analysis must be made for each proposed site based on site-specific data. The methods of doing this are well known and related technical recommendations exist in Germany. These recommendations apply to the planning, construction, operation and post-operational management of salt caverns used for the underground disposal of hazardous wastes. In particular, geotechnical site-specific safety verification, as required by the government's technical regulations on wastes (TA-Abfall) under the section “Underground Disposal”, is required. This safety verification must cover the entire system comprising the waste, the cavern and the surrounding rocks. For this purpose geomechanical models have to be developed. The steps which must be taken when carrying out geological engineering site explorations and when determining geotechnical parameters are discussed. In addition, recommendations are made for the design and construction of underground repositories.

For liquid-filled caverns, long-term sealing from the biosphere is of particular interest. In this instance it must be shown that the natural increase in pressure in the closed cavity due to long-term convergence does not exceed the fracture pressure. A special filled test (scale 1:1) has been performed to study this.  相似文献   

The influence of pressure on the OH valence vibration of zoisite     

B. Winkler  K. Langer  P. G. Johannsen 《Physics and Chemistry of Minerals》1989,16(7):668-671

The influence of pressure on the OH-stretching vibration of zoiste has been studied by single crystal high pressure infrared spectroscopy. A band related to the OH-stretching vibration displayed a linear shift from 3170 cm^?1 at 1 bar to 2795 cm^?1 at 116 kbar. The half-band width increased linearly with respect to pressure from 60 cm^?1 at 1 bar to 500 cm^?1 at 116 kbar. The strength of the absorption of this band is strongly frequency dependent. The high-energy shift of a band at around 2200 cm^?1 on pressure increase indicates that this band is not due to a second OH-stretching vibration as previously suggested by Langer and Lattard (1980).  相似文献   

Tomographic inversion of local earthquake data from the Gioia Tauro basin (south-western Calabria, Italy)   总被引：1，自引：0，他引：1  

R. Raffaele  H. Langer  S. Gresta  F. Moia 《Geophysical Journal International》2006,165(1):167-179

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Multitemporal terrestrial laser scanning point clouds for thaw subsidence observation at Arctic permafrost monitoring sites     

Katharina Anders  Sabrina Marx  Julia Boike  Benjamin Herfort  Evan James Wilcox  Moritz Langer  Philip Marsh  Bernhard Höfle 《地球表面变化过程与地形》2020,45(7):1589-1600

This paper investigates different methods for quantifying thaw subsidence using terrestrial laser scanning (TLS) point clouds. Thaw subsidence is a slow (millimetre to centimetre per year) vertical displacement of the ground surface common in ice-rich permafrost-underlain landscapes. It is difficult to quantify thaw subsidence in tundra areas as they often lack stable reference frames. Also, there is no solid ground surface to serve as a basis for elevation measurements, due to a continuous moss–lichen cover. We investigate how an expert-driven method improves the accuracy of benchmark measurements at discrete locations within two sites using multitemporal TLS data of a 1-year period. Our method aggregates multiple experts’ determination of the ground surface in 3D point clouds, collected in a web-based tool. We then compare this to the performance of a fully automated ground surface determination method. Lastly, we quantify ground surface displacement by directly computing multitemporal point cloud distances, thereby extending thaw subsidence observation to an area-based assessment. Using the expert-driven quantification as reference, we validate the other methods, including in-situ benchmark measurements from a conventional field survey. This study demonstrates that quantifying the ground surface using 3D point clouds is more accurate than the field survey method. The expert-driven method achieves an accuracy of 0.1 ± 0.1 cm. Compared to this, in-situ benchmark measurements by single surveyors yield an accuracy of 0.4 ± 1.5 cm. This difference between the two methods is important, considering an observed displacement of 1.4 cm at the sites. Thaw subsidence quantification with the fully automatic benchmark-based method achieves an accuracy of 0.2 ± 0.5 cm and direct point cloud distance computation an accuracy of 0.2 ± 0.9 cm. The range in accuracy is largely influenced by properties of vegetation structure at locations within the sites. The developed methods enable a link of automated quantification and expert judgement for transparent long-term monitoring of permafrost subsidence. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献   

High-pressure electronic absorption spectroscopy of natural and synthetic Cr<Superscript>3+</Superscript>-bearing clinopyroxenes     

M. N. Taran  H. Ohashi  K. Langer  A. A. Vishnevskyy 《Physics and Chemistry of Minerals》2011,38(5):345-356

Comparison of polarized optical absorption spectra of natural Ca-rich diopsides and synthetic NaCrSi2O6 and LiCrSi2O6 clinopyroxenes, evidences as vivid similarities, as noticeable differences. The similarities reflect the fact that in all cases Cr3+ enters the small octahedral M1-site of the clinopyroxene structure. The differences are due to some iron content in the natural samples causing broad intense near infrared bands of electronic spin-allowed dd transitions of Fe2+(M1, M2) and intervalence Fe2+/Fe3+ charge-transfer transition, and by different symmetry and different local crystal fields strength of Cr3+ in the crystal structures. The positions of the spin-allowed bands of Cr3+, especially of the low energy one caused by the electronic 4 A 2g → 2 T 1g transition, are found to be in accordance with mean M1–O distances. The local relaxation parameter ε calculated for limCr 3+ → 0 from the spectra and interatomic á Cr - O ñ \left\langle {Cr - O} \right\rangle and á Mg - O ñ \left\langle {Mg - O} \right\rangle distances yields a very high value, 0.96, indicating that in the clinopyroxene structure the local lattice relaxation around the “guest” ion, Cr3+, deviates greatly from the “diffraction” value, ε = 0, than in any other known Cr3+-bearing systems studied so far. Under pressure the spin-allowed bands of Cr3+ shift to higher energies and decrease in intensity quite in accordance with the crystal field theoretical expectations, while the spin-forbidden absorption lines remain practically unshifted, but also undergo a strong weakening. There is no evident dependence of the Racah parameter B of Cr3+ reflecting the covalence of the oxygen-chromium bond under pressure: within the uncertainty of determination it may be regarded as practically constant. The values of CrO6 octahedral modulus, k\textpoly\textloc k_{\text{poly}}^{\text{loc}} , derived from high-pressure spectra of natural chromium diopside and synthetic NaCrSi2O6 kosmochlor are very close, ~203 and ~196 GPa, respectively, being, however, nearly twice higher than that of MgO6 octahedron in diopside, 105(4) GPa, obtained by Thompson and Downs (2008). Such a strong stiffening of the structural octahedron, i.e. twice higher value of k\textCr3 + \textloc k_{{{\text{Cr}}^{3 + } }}^{\text{loc}} comparing with that of k\textMg2 + \textloc k_{{{\text{Mg}}^{2 + } }}^{\text{loc}} , may be caused by simultaneous substitution of Ca2+ by larger Na+ in the neighboring M2 sites at so-called jadeite-coupled substitution Mg2+ + Ca2+ → Cr3+ + Na+. It is also remarkable that the values of CrO6 octahedral modulus of NaCrSi2O6 kosmochlor obtained here are nearly twice larger than that of 90(16) GPa, evaluated by high-pressure X-ray structural refinement by Origlieri et al. (2003). Taking into account that the overall compressibility of the clinopyroxene structure should mainly be due to the compressibility of M1- and M2-sites, our k\textCr3 + \textloc k_{{{\text{Cr}}^{3 + } }}^{\text{loc}} -value, ~196 GPa, looks much more consistent with the bulk modulus value, 134(1) GPa.  相似文献   

Polarized electronic absorption spectra of colourless chalcocyanite,CuSO4, with a survey on crystal fields in Cu2+ minerals     

Manfred Wildner  Gerald Giester  Monika Kersten  Klaus Langer 《Physics and Chemistry of Minerals》2014,41(9):669-680

Polarized electronic absorption spectra of colourless chalcocyanite, CuSO₄, have been measured using microscope-spectrometric techniques. The spectra are characterized by a structured and clearly polarized band system in the near-infrared spectral range with components centred at 11,720, 10,545, 9,100, and 7,320 cm^?1, which have been assigned to crystal field d–d transitions of Cu²⁺ cations in pseudo-tetragonally elongated CuO₆ polyhedra with point symmetry C _i ( \(\bar{1}\) ). The polarization behaviour is interpreted based on a D ₂(C ₂″) pseudo-symmetry. Crystal field calculations were performed for the actual triclinic point symmetry by applying the Superposition Model of crystal fields, as well as in terms of a ‘classic’ pseudo-tetragonal crystal field approach yielding the parameters Dq _(eq) = 910, Dt = 395, and Ds = 1,336 cm^?1, corresponding to a cubically averaged Dq _cub = 679 cm^?1. A comparative survey on crystal fields in Cu²⁺ minerals shows that the low overall crystal field strength in chalcocyanite, combined with a comparatively weak pseudo-tetragonal splitting of energy levels, is responsible for its unique colourless appearance among oxygen-based Cu²⁺ minerals. The weak crystal field in CuSO₄ can be related to the lower position of the SO₄ ^2? anion compared to, e.g. the H₂O molecule in the spectrochemical series of ligands.  相似文献   

Compression moduli of Cr3+-centered octahedra in a variety of oxygen-based rock-forming minerals     

K. Langer  M. N. Taran  A. N. Platonov 《Physics and Chemistry of Minerals》1997,24(2):109-114

High-pressure electronic absorption spectra at room temperature and at pressures 10^?4<P[GPa]<8 were measured in the spectral range 380<λ[nm] <780(26218>ν?[cm^?1]>12820) on analysed single crystal slabs, about 20?μm thick, of Cr³⁺-bearing spinel (I), kyanite (II), corundum (III), pyrope (IV) and uvarovite (V) using DAC-cell techniques in combination with single-beam microscopespectrometry. Ligand field theoretical evaluation of the spectra yielded following results: (i)?the octahedral crystal field parameter, 10Dq_Cr3+[6], linearly shifts on increasing pressure to higher energies with slopes, (δ10Dq_Cr3+[6]/δP), of 103.1 (I), 99.5 (II), 104.0 (III), 111.7 (IV) and 110.3?[cm^?1/GPa] (V) (reliability parameters r≥0.92), (ii)?The Racah-parameter B_Cr3+[6], reflecting the covalency of the Cr–O bonds, does not significantly change with pressure up to 8?GPa, in those cases where it could be evaluated from the spectra (III, IV, V). This result is contrary to the behaviour of B_Cr3+[6] with increasing temperature (Taran et?al. 1994) and shows that P and T are not inversely correlated parameters with respect to B_Cr3+[6], a decrease of which reflects an increase in covalency. (iii)?This result enabled to extract octahedral compression moduli, k_Cr3+[6], from the pressure slopes of 10Dq_Cr3+[6]: 312+48 (I), 297+70 (II), 298+44 (III), 275+35 (IV), 257+32?GPa (V). Quotients k_cr3+[6]/k_bulk,phase are nearly the same (ca. 1.6) for I, II, IV and V but significantly lower (ca. 1.1) for III. Deviations between spectroscopically determined k_Cr3+[6] and published k_Al[6], obtained by HP-XRD on ruby and pyrope, are interpreted by lattice strain induced by [Cr³⁺,?Al3+?1]^[6] substitution.  相似文献   

Single crystal MFTIR-spectra at various temperatures of synthetic end member garnets in the OH-valence vibrational region     

A. Hösch  K. Langer 《Physics and Chemistry of Minerals》1996,23(4-5):305-306

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Hyperonic equation of state     

William D. Langer  Leonard C. Rosen 《Astrophysics and Space Science》1970,6(2):217-227

An equation of state for cold matter at neutron star densities, >10¹⁴ gm/cm³, is evaluated. The gas is considered to be a degenerate mixture of neutrons, protons, leptons, hyperons and massive baryons. We derive the equilibrium equations including the effects of nuclear interactions among all the hadrons.  相似文献