断裂带震源机制节面聚类确定断裂带产状方法及在2021年漾濞地震序列中的应用

一条断裂带上发生地震的破裂面通常与断裂带形状接近,同一地震破裂带上大量震源机制节面中应该有集中于断层面形状的一个集合,求出此集合的节面中心就可以得到断裂带的几何形状.根据这个原理,本研究给出了震源机制节面之间距离的方法,将带有噪声、基于密度的空间聚类方法(DBSCAN)应用于震源机制的节面聚类分析,并应用于2021年云...     

节点地震采集系统发展现状

地震仪器是地球物理勘探的核心装备,伴随地震勘探技术的进步,几年即可推出一代新设备。近年来,随着节点技术的发展,节点地震采集系统逐步应用在各个领域,且效果较好。结合地球物理勘探技术的发展需求,介绍主流陆地节点地震仪器的特点与应用,分析存在的问题及改进方向,希望促进对节点仪器的了解和应用。     

Three-dimensional modelling of soil organic carbon density and carbon sequestration potential estimation in a dryland farming region of China

Soil organic carbon density(SOCD) and soil organic carbon sequestration potential(SOCP) play an important role in carbon cycle and mitigation of greenhouse gas emissions. However, the majority of studies focused on a two-dimensional scale, especially lacking of field measured data. We employed the interpolation method with gradient plane nodal function(GPNF) and Shepard(SPD) across a range of parameters to simulate SOCD with a 40 cm soil layer depth in a dryland farming region(DFR) of China. The SOCP was estimated using a carbon saturation model. Results demonstrated the GPNF method was proved to be more effective in simulating the spatial distribution of SOCD at the vertical magnification multiple and search point values of 3.0×10~6 and 25, respectively. The soil organic carbon storage(SOCS) of 40 cm and 20 cm soil layers were estimated as 22.28×10~(11) kg and 13.12×10~(11) kg simulated by GPNF method in DFR. The SOCP was estimated as 0.95×10~(11) kg considered as a carbon sink at the 20–40 cm soil layer. Furthermore, the SOCP was estimated as –2.49×10~(11) kg considered as a carbon source at the 0–20 cm soil layer. This research has important values for the scientific use of soil resources and the mitigation of greenhouse gas emissions.     

Nodal and Mixed Finite Elements for the Numerical Homogenization of 3D Permeability

The aim of upscaling is to determine equivalent homogeneous parameters at a coarse-scale from a spatially oscillating fine-scale parameter distribution. To be able to use a limited number of relatively large grid-blocks in numerical oil reservoir simulators or groundwater models, upscaling of the permeability is frequently applied. The spatial fine-scale permeability distribution is generally obtained from geological and geostatistical models. After upscaling, the coarse-scale permeabilities are incorporated in the relatively large grid-blocks of the numerical model. If the porous rock may be approximated as a periodic medium, upscaling can be performed by the method of homogenization. In this paper the homogenization is performed numerically, which gives rise to an approximation error. The complementarity between two different numerical methods – the conformal-nodal finite element method and the mixed-hybrid finite element method – has been used to quantify this error. These two methods yield respectively upper and lower bounds for the eigenvalues of the coarse-scale permeability tensor. Results of 3D numerical experiments are shown, both for the far field and around wells.     

矛盾符号比与区域构造的关系及其应用

通过十几年来对小震综合节面解矛盾符号比与强震关系的研究,发现矛盾符号比与区域构造有关.根据区域构造不同适当划分小区,则有的小区中矛盾符号比与强震关系明显,呈现“高-低-发震-高”的变化趋势.这样的小区形成强震孕育的“敏感点”其他小区则无明显变化.一方面可以从“敏感点”中捕捉未来大震的信息;另一方面,根据小区中矛盾符号的变化特点还可以判断地震序列的性质和预测强余震.     

The Restructuring of Air Transport Linkages in the New Europe*

Air transportation is a vital component of economic interchange. This paper explores changes in the European air transport network that have occurred since the political and economic reorientation of the former Eastern bloc and the restructuring of the European Union. Using basic connectivity measures, it was found that East-West nodal linkage within the network has improved, leading the way for full economic integration of the region.     

The influence of long tides on ecosystem dynamics in the Barents Sea

The Barents Sea ecosystem has been associated with large biomass fluctuations. If there is a hidden deterministic process behind the Barents Sea ecosystem, we may forecast the biomass in order to control it. This presentation concludes, for the first time, investigations of a long data series from North Atlantic water and the Barents Sea ecosystem. The analysis is based on a wavelet spectrum analysis from the data series of annual mean Atlantic sea level, North Atlantic water temperature, the Kola section water temperature, and species from the Barents Sea ecosystem.The investigation has identified dominant fluctuations correlated with the 9.3-yr phase tide, the 18.6-yr amplitude tide, and a 74-yr superharmonic cycle in the North Atlantic water, Barents Sea water, and Arctic data series. The correlation between the tidal cycles and dominant Barents Sea ecosystem cycles is estimated to be R=0.6 or better. The long-term mean fluctuations correlate with the 74-yr superharmonic cycle. The wavelets analysis shows that the long-term 74-yr cycle may introduce a phase reversal in the identified 18-yr periods of temperature and salinity. The present analysis suggests that forced vertical and horizontal nodal tides influence the ocean's thermohaline circulation, and that they behave as a coupled non-linear oscillation system.The Barents Sea ecosystem analysis shows that the biomass life cycle and the long-term fluctuations correlate better than R=0.5 to the lunar nodal tide spectrum. Barents Sea capelin has a life cycle related to a third harmonic of the 9.3-yr tide. The life cycles of shrimp, cod, herring, and haddock are related to a third harmonic of the 18.6-yr tide. Biomass growth was synchronized to the lunar nodal tide. The biomass growth of zooplankton and shrimp correlates with the current aspect of lunar nodal tidal inflow to the Barents Sea. The long-term biomass fluctuation of cod and herring is correlated with a cycle period of about 3×18.6=55.8 yr. This analysis suggests that we may understand the Barents Sea ecosystem dynamic as a free-coupled oscillating system to the forced lunar nodal tides. This free-coupled oscillating system has a resonance related to the oscillating long tides and the third harmonic and superharmonic cycles.     

Impacts of human interventions on the seasonal and nodal dynamics of the M2 and K1 tidal constituents in Lingdingyang Bay of the Zhujiang River Delta,China

Natural and human-induced changes may exert considerable impacts on the seasonal and nodal dynamics of M₂ and K₁ tidal constituents. Therefore, quantifying the influences of these factors on tidal regime changes is essential for sustainable water resources management in coastal environments. In this study, the enhanced harmonic analysis was applied to extract the seasonal variability of the M₂ and K₁ tidal amplitudes and phases at three gauging stations along Lingdingyang Bay of the Zhujiang River Delta. The seasonal dynamics in terms of tidal wave celerity and amplification/damping rate were used to quantify the impacts of human-induced estuarine morphological alterations on M₂ and K₁ tidal hydrodynamics in inner and outer Lingdingyang Bay. The results show that both tidal amplification/damping rate and wave celerity were considerably increased from the pre-anthropogenic activity period (Pre-AAP) to the post-anthropogenic activity period (Post-AAP) excepting the tidal amplification/damping rate in outer Lingdingyang Bay, and the variations in outer Lingdingyang Bay was larger than those in inner Lingdingyang Bay. The alterations in these two parameters were more significant in flood season than in dry season in both inner and outer Lingdingyang Bay. The seasonal variability of M₂ and K₁ tidal amplitudes were further quantified using a regression model accounting for the 18.61-year lunar nodal modulation, where this study observes a considerable alteration in M₂ constituent owing to human interventions. During the Post-AAP, the M₂ amplitudes at the downstream station were larger than those that would have occurred in the absence of strong human interventions, whereas the opposite was true for the upstream station, leading to a substantial decrease in tidal amplification in outer Lingdingyang Bay. However, it is opposite in inner Lingdingyang Bay. The underlying mechanism can be primarily attributed to channel deepening and narrowing caused by human interventions, that resulted in substantial enlargement of the bay volume and reduced the effective bottom friction, leading to faster wave celerity and stronger amplified waves.