Travel time residuals in southeastern Europe

The Pn travel time relative residuals, in respect to a crustal model of the Aegean area, have been determined for 103 permanent seismological stations in southeastern Europe, western Turkey and the Middle East. The values of these residuals are considered to depend mainly on the crustal thickness beneath the seismological stations. Based on these values seven regions with different crustal thickness, varying between 31 Km and 42 Km, have been defined. The crust in these regions is continental. A region with very high negative residuals has been defined in the Middle East (Egypt, Israel, Lebanon). These negative residuals are attributed to different crustal structure of the eastern Mediterranean (oceanic crust with an extra thick sedimentary layer) and not the crustal thickness at the station sites.Independently from the interpretation, these Pn residuals can be used successfully to considerably improve (up to 2 Km) the determination of the earthquake foci locations.     

多层基础隔震房屋结构在水平地震力作用下的振动传递

文章将周期结构原理与导纳方法结合起来，分析了带复合结构单元的有阻尼的有限周期系统的波传播和振动特性，得到了有限周期结构自振频率的一般表达式。     

The "Little Ice Age" and its Geomorphological Consequences in Mediterranean Europe

Alpine glacier advances in the "Little Ice Age" took place in the decades around 1320, 1600, 1700 and 1810. They were the outcome of snowier winters and cooler summers than those of the twentieth century. Documentary records from Crete in particular, and also from Italy, southern France and southeast Spain point to a greater frequency in Mediterranean Europe's mountainous regions of severe floods, droughts and frosts at times of "Little Ice Age" Alpine glacier advances. Deluges, when more than 200 mm of rain fall within 24 hours, are most frequent on mountainous areas near the coast. An instance is given of the geomorphological consequences of a great deluge which struck the Tech valley in the eastern Pyrenees on 17 October 1940. An increased frequency of deluges, probably at times when Alpine glaciers were advancing in the "Little Ice Age" and earlier in the Holocene, in areas known to be tectonically unstable and underlain by soft sediments, could better explain the occurrence of fluvial terraces in Mediterranean Europe sometimes known as the "younger fill", than soil erosion resulting from deforestation.     

A crustal seismic velocity model for the UK, Ireland and surrounding seas

A regional model of the 3-D variation in seismic P -wave velocity structure in the crust of NW Europe has been compiled from wide-angle reflection/refraction profiles. Along each 2-D profile a velocity–depth function has been digitised at 5 km intervals. These 1-D velocity functions were mapped into three dimensions using ordinary kriging with weights determined to minimise the difference between digitised and interpolated values. An analysis of variograms of the digitised data suggested a radial isotropic weighting scheme was most appropriate. Horizontal dimensions of the model cells are optimised at 40 × 40 km and the vertical dimension at 1 km. The resulting model provides a higher resolution image of the 3-D variation in seismic velocity structure of the UK, Ireland and surrounding areas than existing models. The construction of the model through kriging allows the uncertainty in the velocity structure to be assessed. This uncertainty indicates the high density of data required to confidently interpolate the crustal velocity structure, and shows that for this region the velocity is poorly constrained for large areas away from the input data.     

Mapping landslide susceptibility from small datasets: A case study in the Pays de Herve (E Belgium)

A landslide susceptibility map is proposed for the Pays de Herve (E Belgium), where large landslides affect Cretaceous clay outcrop areas. Based on a Bayesian approach, this GIS-supported probabilistic map identifies the areas most susceptible to deep landslides. The database is comprised of the source areas of ten pre-existing landslides (i.e. a sample of 154 grid cells) and of six environmental data layers, namely lithology, proximity to active faults, slope angle and aspect, elevation and distance to the nearest valley-floor. A 30-m-resolution DEM from the Belgian National Geographical Institute is used for the analysis. Owing to the small size of the sample, a special cross-validation procedure of the susceptibility map is performed, which uses in an iterative way each of the landslides to test the predictive power of the map derived from the other landslides. Four different sets of variables are used to produce four susceptibility maps, whose prediction curves are compared. While the prediction rates associated with the models not involving the “proximity to active fault” criterion are comparable to those of the models considering this variable, strong weaknesses inherent in the fault data on which the latter rely suggest that the final susceptibility map should be based on a model that excludes any reference to fault. This highlights the difference between a triggering factor and determining factors, and in the same time broadens the scope of the produced map. A single reactivated slide is also used to test the possibility of predicting future reactivation of existing landslides in the area. Finally, the need for geomorphological control over the mathematical treatment is underlined in order to obtain realistic prediction maps.     

ISLAND SOJOURNS

ABSTRACT. Islands have long held a central place in Western cultures' mythical geographies. They have been associated for centuries with heroic journeys and holy quests, imagined realms of magical transformations. Islands have also been sites of significant rites of passage, and they continue to perform this function in the modern secular world. Today, popular islomania is expressed in the frequency of seasonal sojourning on European and American archipelagos. No longer destinations of permanent residence, islands now provide access to a sense of temporal and spatial rootedness that is no longer available on mainlands. They loom large on the mental maps even of those who rarely, if ever, visit them.     

A method to estimate hydraulic conductivity from bulk geochemical compositions

A new method has been developed to estimate the hydraulic conductivity in unconsolidated aquifers. The method uses bulk geochemical compositions correlated with hydraulic conductivities measured by pumping tests. The concept is based on a general rule that hydraulic conductivity is principally controlled by grain-size distribution and particle shape,both of which relate to mineralogical composition. Using a MINLITH algorithm, normative mineralogical compositions can be derived from bulk geochemical compositions economically and expediently, and then correlated to the hydraulic conductivity determined by pumping tests in the field. In this study, 202 sediment samples from nine unconsolidated aquifers were analyzed by X-ray fluorescence. Although hydraulic conductivity does not show a definite relationship with geochemical compositions, it does demonstrate a linear logarithmic equation to the content of normative earthy minerals. However, linear regressed equations should not be applied to aquifers composed of medium to coarse sand and gravel sizes due to interference from lithic fragments. In addition, this equation tends to overestimate hydraulic conductivity possibly because the effect of compaction is ignored in this study.     

SEDIMENT BUDGETS AND RATES OF SEDIMENT TRANSFER ACROSS COLD ENVIRONMENTS IN EUROPE: A COMMENTARY

The sediment mass balance equation is the fundamental concept which underpins most sediment budget studies in cold climate environments. In these environments the interchange between water and ice plays a predominant geomorphological role. Such environments show a large variety of geomorphic processes which are conditioned by both contemporary environmental conditions but also the legacy of past events. In the northern Europe/Arctic fringe these cold regions are distributed in a fragmented fashion and are likely to be very sensitive to climate change scenarios. The significance of such changes for sediment transfer can only be established if we have good contemporary process understanding, the necessary tools to carefully monitor and model such changes, and can apply such methods at appropriate scales which integrate both sediment sources and sinks.     

Two-dimensional power series solution for non-axisymmetrical transport in a radially convergent tracer test with scale-dependent dispersion

It has been known for many years that dispersivity increases with solute travel distance in a subsurface environment. The increase of dispersivity with solute travel distance results from the significant variation of hydraulic properties of heterogeneous media and was identified in the literature as scale-dependent dispersion. This study presents an analytical solution for describing two-dimensional non-axisymmetrical solute transport in a radially convergent flow tracer test with scale-dependent dispersion. The power series technique coupling with the Laplace and finite Fourier cosine transform has been applied to yield the analytical solution to the two-dimensional, scale-dependent advection–dispersion equation in cylindrical coordinates with variable-dependent coefficients. Comparison between the breakthrough curves of the power series solution and the numerical solutions shows excellent agreement at different observation points and for various ranges of scale-related transport parameters of interest. The developed power series solution facilitates fast prediction of the breakthrough curves at any observation point.     

丘陵浅山地区风速幂指数及其在大气环境质量预测中的应用

根据丘陵浅山地区8个测点低空风速实测资料进行风速廓线拟合，求得风速幂指数，将大气环境质量预测中的风速模式化，用来预测大气污染物的浓度分布。