The fine structure of the normal incidence synthetic seismogram     

Enders A. Robinson  Sven Treitel 《Geophysical Journal International》1978,53(2):289-309

Summary . The spectral function of a perfectly elastic, horizontally stratified medium has been demonstrated previously to provide an attractive formulation to describe the properties of the one-dimensional synthetic seismogram (Robinson & Treitel). Here we examine the mathematical framework of the Model in still greater detail. Knowledge of this fine structure of the synthetic seismogram leads to the solution of two particular seismic inverse problems. First, we consider a layered medium with an arbitrary surface reflection coefficient c _o, where | c _o|<1, and which contains an impulsive source immediately above the surface. Given the corresponding synthetic seismogram, we develop an inverse, or backward recursion formalism which recovers the entire series of original reflection coefficients. Second, we consider a similar problem for an impulsive source located just below the surface. Both inversion procedures constitute a continuation of the work of Goupillaud and of Sherwood & Trorey, and represent a generalization of the classical technique originally proposed by Kunetz which, however, only holds for the marine case, c_o =±1. The present approach is not so constrained and thereby becomes applicable to land seismograms as well.
If products of third or higher order in the reflection coefficients can be neglected, significant simplifications arise in the theory. In that event the usual representation of the synthetic seismogram as a ratio of two polynomials in the complex variable z becomes particularly revealing. The numerator polynomial is then approximately equal to the z transform of the reflection coefficient series, while the denominator polynomial is approximately equal to the z transform of the autocorrelation of these reflection coefficients. The resulting simplified theory affords important computational savings in the appropriate backward recursion algorithms.  相似文献   

Damage Potential and Losses Resulting from Snow Avalanches in Settlements of the Canton of Grisons,Switzerland   总被引：2，自引：1，他引：1  

Sven?FuchsEmail author  Michael?Bründl 《Natural Hazards》2005,34(1):53-69

In the field of natural hazards, risk is usually expressed as a function of probability of occurrence and damage potential. A key factor in the development of avalanche risk is a change in damage potential. In this paper, the development of damage potential and losses is analysed for settlements in the canton of Grisons, Switzerland for the period between 1950 and 2000. The spatial development patterns of the residential population and the insured value of buildings on a municipal level are described. These patterns are overlain by an accentuated occurrence of avalanches that caused damage to buildings. Extensive results from areas threatened by avalanches in the municipality of Davos are presented. Although the natural avalanche activity remained constant during the last decades, the total amount of damage decreased due to mitigation measures. The example of the municipality of Davos shows that mitigation measures are able to compensate an increase of tangible assets which leads to a reduced avalanche risk compared to earlier decades.  相似文献   

Acclimations of macroalgae as reflected in photosynthetic parameters derived from PAM fluorometry, and possible implications for abundance patterns     

Shai Saroussi  & Sven Beer 《Marine Ecology》2007,28(3):377-383

The presences of the common macroalgae Ulva sp. and Jania rubens vary between seasons along the Israeli Mediterranean intertidal zone. To reveal some of the potential acclimation mechanisms of these algae, we examined their photosynthetic traits during the year using rapid light curves (RLC) derived from pulse amplitude modulated (PAM) fluorometry. In addition, the relationships between those photosynthetic traits and the relative abundances of the two algae were investigated. Ulva sp. showed high maximal electron transport rates (ETR_max) (49.7–68.8 μmol electrons m⁻² s⁻¹) and onsets of light saturation values (E_k) (75.8–85.6 μmol photons m⁻² s⁻¹) in the winter months of December–February, while low values were found in the summer months of June–July (5.2–20.6 μmol electrons m⁻² s⁻¹ and 6.0–23.7 μmol photons m⁻² s⁻¹, respectively). At noon time (during the highest irradiance of the day), the maximal effective quantum yield (Y₀) did not vary significantly during the year. These results indicate that seasonal irradiance influences the number of reaction centres per thallus area. Both algae showed depressions in Y₀ at noon (23.8% for Ulva sp. and 20.3% for Jania rubens), indicating an efficient non‐photochemical quenching mechanism. A positive correlation between the relative abundance and the photosynthetic parameter Y₀ was found for Jania rubens when Y₀ was sampled in the morning or noon, indicating that growth rate and primary production for this alga can be estimated from RLCs. No such correlation was found for Ulva sp., indicating that, in addition to photosynthetic traits, the relative seasonal abundance of this alga is influenced by other factors such as grazing and/or catastrophic events.  相似文献   

Regional maximum rainfall analysis using L-moments at the Titicaca Lake drainage,Peru     

Fernández-Palomino  Carlos Antonio  Lavado-Casimiro  Waldo Sven 《Theoretical and Applied Climatology》2017,129(3-4):1295-1307

Theoretical and Applied Climatology - The present study investigates the application of the index flood L-moments-based regional frequency analysis procedure (RFA-LM) to the annual maximum 24-h...  相似文献   

The role of iron in tetrahedrite and tennantite determined by Rietveld refinement of neutron powder diffraction data     

Jens Wenzel Andreasen  Emil Makovicky  Bente Lebech  Sven Karup Møller 《Physics and Chemistry of Minerals》2008,35(8):447-454

Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu_12?xFe_xSb₄S₁₃) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu_12?xFe_xAs₄S₁₃) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I $ \ifmmode\expandafter\bar\else\expandafter\=\fi{4} Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu_12−xFe_xSb₄S₁₃) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu_12−xFe_xAs₄S₁₃) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I 3 m). The refinement results also confirm that M2 is a split (24g), flat-pyramidal site situated statistically on both sides of the S1−S1–S2 triangle. In tetrahedrite, this split is about 0.6 ?, in tennantite about 0.7 ?. Trends in bond lengths and magnitude of the M2 split were evaluated by means of linear regression with Fe concentration as the independent variable.  相似文献   

Joint atmospheric-terrestrial water balances for East Africa: a WRF-Hydro case study for the upper Tana River basin     

Kerandi  Noah  Arnault  Joel  Laux  Patrick  Wagner  Sven  Kitheka  Johnson  Kunstmann  Harald 《Theoretical and Applied Climatology》2018,131(3-4):1337-1355

Theoretical and Applied Climatology - For an improved understanding of the hydrometeorological conditions of the Tana River basin of Kenya, East Africa, its joint atmospheric-terrestrial water...  相似文献   

Dealing with climate science denialism: experiences from confrontations with other forms of pseudoscience     

Sven Ove Hansson 《Climate Policy》2018,18(9):1094-1102

Climate science denialism is a form of pseudoscience. This contribution provides proposals for how to counter it, based on previous research on the demarcation between science and pseudoscience and on the author’s experience of tackling other forms of pseudoscience. Science denialism has much in common with other variants of pseudoscience, but it also has characteristics of its own. In particular, it is much more prone than other forms of pseudoscience to seek conflicts with genuine science. Like other science denialists, those attacking climate science have fabricated a large number of fake controversies in issues where there is no authentic scientific controversy. The defence of climate science against science denial has to take this into account. There is no reason to accept the denialists’ agenda or to treat their claims as legitimate alternatives to science. Climate science should primarily be presented to the public in ways that are independent of denialist activities, rather than reactively in response to those activities. Disclosures of the strategies, motives and funding of denialism are important contributions to the public understanding of the fake controversies. It is also important to document the scientific consensus and make it known. The public defence of climate science is an important and urgent undertaking, and active contributions by as many scientists as possible are needed.

Key policy insights

• Climate science denialism is a form of pseudoscience, and much can be learned from confrontations with other types of pseudoscience.

• The creation of fake controversies is a key strategy of climate science denialism. It is important to expose this strategy and not to accept denialists’ choice of an agenda.

• ‘Equal time’ arrangements should be rejected since they put the truthful side at a disadvantage. It takes more time to refute a single lie than to deliver ten new ones.

• The experience from fighting tobacco science denialism shows that it is highly efficient to expose the hidden operations, funding and motives behind denialism.

• As many scientists as possible should take part in the public defence of climate science. This is one of the best ways to show our consensus.

  相似文献   

Rockfall in the Port Hills of Christchurch: Seismic and non‐seismic fatality risk on roads          下载免费PDF全文

Stefan Unterrader  Peter Almond  Sven Fuchs 《New Zealand geographer》2018,74(1):3-14

Numerous rockfalls released during the 2010–2011 Canterbury earthquake sequence affected vital road sections for local commuters. We quantified rockfall fatality risk on two main routes by adapting a risk approach for roads originally developed for snow avalanche risk. We present results of the collective and individual fatality risks for traffic flow and waiting traffic. Waiting traffic scenarios particularly address the critical spatial‐temporal dynamics of risk, which should be acknowledged in operational risk management. Comparing our results with other risks commonly experienced in New Zealand indicates that local rockfall risk is close to tolerability thresholds and likely exceeds acceptable risk.  相似文献   

Tsunami simulations on several scales     

Sven Harig  Chaeroni  Widodo S. Pranowo  Jörn Behrens 《Ocean Dynamics》2008,58(5-6):429-440

The tsunami event generated by the great Sumatra–Andaman earthquake on 26 December 2004 was simulated with the recently developed model TsunAWI. The model is based on the finite element method, which allows for a very flexible discretization of the model domain. This is demonstrated by a triangulation of the whole Indian Ocean with a resolution of about 14 km in the deep ocean but a considerably higher resolution of about 500 m in the coastal area. A special focus is put on the Banda Aceh region in the Northern tip of Sumatra. This area was heavily hit by the tsunami and the highest resolution in this area is about 40 m in order to include inundation processes in the model simulation. We compare model results to tide gauge data from all around the Indian Ocean, to satellite altimetry, and field measurements of flow depth in selected locations of the Aceh region. Furthermore, we compare the model results of TsunAWI to the results of a nested grid model (TUNAMI-N3) with the same initial conditions and identical bathymetry and topography in the Aceh region. It turns out that TsunAWI gives accurate estimates of arrival times in distant locations and in the same mesh gives good inundation results when compared to field measurements and nested grid results.  相似文献   

Trends in rainfall and temperature in the Peruvian Amazon–Andes basin over the last 40 years (1965–2007)     

Waldo Sven Lavado Casimiro  David Labat  Josyane Ronchail  Jhan Carlo Espinoza  Jean Loup Guyot 《水文研究》2013,27(20):2944-2957

The hydroclimatology of the Peruvian Amazon–Andes basin (PAB) which surface corresponding to 7% of the Amazon basin is still poorly documented. We propose here an extended and original analysis of the temporal evolution of monthly rainfall, mean temperature (T_mean), maximum temperature (T_max) and minimum temperature (T_min) time series over two PABs (Huallaga and Ucayali) over the last 40 years. This analysis is based on a new and more complete database that includes 77 weather stations over the 1965–2007 period, and we focus our attention on both annual and seasonal meteorological time series. A positive significant trend in mean temperature of 0.09 °C per decade is detected over the region with similar values in the Andes and rainforest when considering average data. However, a high percentage of stations with significant T_mean positive trends are located over the Andes region. Finally, changes in the mean values occurred earlier in T_max (during the 1970s) than in T_min (during the 1980s). In the PAB, there is neither trend nor mean change in rainfall during the 1965–2007 period. However, annual, summer and autumn rainfall in the southern Andes presents an important interannual variability that is associated with the sea surface temperature in the tropical Atlantic Ocean while there are limited relationships between rainfall and El Niño‐Southern Oscillation (ENSO) events. On the contrary, the interannual temperature variability is mainly related to ENSO events. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献