D-Rex, a program for calculation of seismic anisotropy due to crystal lattice preferred orientation in the convective upper mantle   总被引：1，自引：0，他引：1  

Édouard Kaminski  Neil M. Ribe  Jules T. Browaeys 《Geophysical Journal International》2004,158(2):744-752

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How deep was the Dudley (UK) earthquake of 22 September 2002?     

Ross?HeyburnEmail author  David?Bowers  Neil?Selby  Alan?Douglas 《Journal of Seismology》2005,9(1):61-71

On 22 September 2002, the largest UK earthquake (m_b4.3) of the last 10 years occurred near the town of Dudley in the West Midlands. Here we determine the earthquake focal mechanism and depth using data from stations at regional and teleseismic distances. Short-period teleseismic seismograms are interpreted in terms of P and surface reflections pP and sP. This analysis suggests that the source depth is deeper than the 9.7 km initially determined by the British Geological Survey (BGS). The relative amplitude method is applied to four teleseismic seismograms to support our interpretation of the surface reflections, and constrain the focal mechanism. Our preferred focal mechanism, a near vertical strike-slip with _s = 94°, = 88° and = –179°, is in reasonable agreement with a moment tensor determined by the Swiss Seismological Service. Synthetic regional surface wave seismograms match the observed seismograms for a model focal depth of 19.5 (±3.0) km and scalar moment, M₀, of 3.2 × 10¹⁵ N m. Our results emphasize that due to the well-known trade-off between depth and M₀ from inversions of long period (0.02–0.1 Hz) surface waves, it is preferable to combine long- and short-period data to constrain reliably the depth and hence estimate M₀. Our focal mechanism and depth are further validated by generating short-period synthetic seismograms that match the observations.  相似文献   

A Coupled Calibration and Modelling Approach to the Understanding of Dry-Land Lake Oxygen Isotope Records     

Matthew D.?JonesEmail author  Melanie J.?Leng  C. Neil?Roberts  Murat?Türke?  Rana?Moyeed 《Journal of Paleolimnology》2005,34(3):391-411

Comparisons between climate proxies and instrumental records through the last two centuries are often used to understand better the controls on palaeoarchives and to find relationships that can be used to quantify changes in pre-instrumental climate. Here we compare an 80-year-long annually resolved oxygen isotope record from Nar Gölü, Turkey, a varved lake sequence, with instrumental records of temperature, precipitation, wind speed, relative humidity and calculated values of evaporation, all of which are known to be possible controls on lake oxygen isotope systems. Significant relationships are found between the isotope record and summer temperatures and evaporation suggesting these are dominant controls on the isotope hydrology of this non-outlet lake. Modelling the stable isotope hydrology of the lake system allows these relationships to be tested independently. We show that the isotope record follows the same trends in the temperature and evaporation records but that, even when combined, these two climatic factors cannot fully explain the magnitude of change observed in the isotope record. The models show the lake system is much less sensitive to changes in evaporation and temperature than the climate calibration suggests. Additional factors, including changes in the amount of precipitation, are required to amplify the isotope change. It is concluded that proxy-climate calibrations may incorrectly estimate the amplitude of past changes in individual climate parameters, unless validated independently.  相似文献   

Two problems in WKBJ theory: the interpolation of sampled velocity profiles and the use of frequency-dependent, complex velocities     

L. Neil Frazer 《Geophysical Journal International》1983,72(1):193-211

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Theories of Underdevelopment: A Response to Reitsma     

Neil Smith 《The Professional geographer》1982,34(3):332-337

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Kirchhoff–Helmholtz reflection seismograms in a laterally inhomogeneous multi-layered elastic medium – II. Computations     

Mrinal K. Sen  L. Neil Frazer 《Geophysical Journal International》1985,82(3):415-437

Summary. High-frequency reflection and refraction seismograms for laterally variable multi-layered elastic media are computed by using the frequency domain elastic Kirchhoff–Helmholtz (KH) theory of Frazer and Sen. Both source and receiver wavefields are expanded in series of generalized rays and then elastic (KH) theory is applied to determine the coupling between each source ray and each receiver ray at each interface. The motion at the receiver is given as a series of integrals, one for each generalized ray. We use geometrical optics and plane wave reflection and transmission coefficients for rapid evaluation of the integrand. When the source or the receiver ray field has caustics on the surface of integration geometrical ray theory breaks down and this gives rise to singularities in the KH integrand. We repair this using methods suggested by Frazer and Sen.
Examples of reflection seismograms for 2-D structures computed by elastic KH theory are shown. Those for a vertical fault scarp structure are compared with the seismograms obtained by physical modelling. Then OBS data obtained from the mid-America trench offshore Guatemala area are analysed by computing KH synthetics for a velocity model that has been proposed for that area. Our analysis indicates the existence of a small low-velocity zone off the trench axis.
No head wave arrivals are obtained in our KH synthetics since we do not consider multiple interactions of a ray with an interface. The nearly discontinuous behaviour of elastic R/T coefficients near the critical angle causes small spurious phases which arrive later than the correct arrivals.  相似文献   

Use of the spherical layer matrix in inhomogeneous media     

L. Neil FIazer 《Geophysical Journal International》1977,50(3):743-749

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Bringing in Race     

Olivia Mitchell  Neil Smith 《The Professional geographer》1990,42(2):232-234

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Structure and kinematics of the northern Simano Nappe, Central Alps, Switzerland     

Roger Rütti  Michael Maxelon  Neil S. Mancktelow 《Eclogae Geologicae Helvetiae》2005,98(1):63-81

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Comment on “An experimental study of oxygen isotope fractionation between inorganically precipitated aragonite and water at low temperatures” by G.-T. Zhou and Y.-F. Zheng     

Sang-Tae Kim  James R. O’Neil 《Geochimica et cosmochimica acta》2005,69(12):3195-3197

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