The first peak ground motion attenuation relationships for North of Vietnam

The first attenuation relationships of peak ground acceleration (PGA) and peak ground velocity (PGV) for northern Vietnam are obtained in this study. Ground motion data are collected by a portable broadband seismic network in northern Vietnam as a part of cooperation between the Institute of Geophysics, Vietnamese Academy of Science and Technology, Vietnam and Institute of Earth Sciences, Academia Sinica, Taiwan. The database comprises a total of 330 amplitude records by 14 broadband stations from 53 shallow earthquakes, which were occurred in and around northern Vietnam in the period between 01/2006 and 12/2009. These earthquakes are of local magnitudes between 1.6 and 4.6, focal depths less than 30 km, and epicentral distances less than 500 km. The new attenuation relationships for PGA and PGV are:

log₁₀(PGA)=-0.987+0.7521M_L-log₁₀(R)-0.00475R,     

Laboratory organic matter maturation at high pressures: heat-up effect on vitrinite reflectance

A laboratory study was conducted to assess the effect of heat-up to high diagenetic to low metamorphic temperatures on vitrinite reflectance (VR) at high pressures using the same heat-up processes, apparatus and starting material as those employed in prior experimental studies on huminite/vitrinite maturation. ??Heat-up?? is the isobaric increase in temperature of an organic matter maturation experiment from room temperature to the desired run temperature T ^ehu (T ^ehu ?=?temperature at the end of heat-up). The experiments were performed on xylite of swamp cypress and used a heating rate of 50?°C/min. These confined system maturation experiments were carried out at 10?kbar and involved temperatures T ^ehu ranging from 175 to 450?°C. Additional experiments were conducted at pressures of 5, 20 and 25?kbar to evaluate the influence of pressure on the effect of heat-up on VR. At 10?kbar, results of this study show that heat-up does not influence VR for T ^ehu ?< ~270?°C. This absence of maturation is viewed as the result of an activation time delaying vitrinite maturation at these diagenetic to very low metamorphic temperatures. For T ^ehu ?> ~270?°C, heat-up has a significant effect on VR at 10?kbar: VR greatly increases with T ^ehu during the short heat-up event. This effect of heat-up on VR points out the rapid kinetics of the initial VR increase. Increasing pressure reduces VR increase gained during heat-up. Obviously, pressure retards the initial VR increase and thus controls organic matter maturation. In addition to temperature, the formulation of VR evolution rate equation must consider pressure, activation time and VR gained during heat-up.     

基于典型物候特征的MODIS-EVI时间序列数据 农作物种植面积提取方法 —小区域冬小麦实验研究

利用MODIS植被指数时间序列这一特性,以北京市通州及周边为实验区,冬小麦种植面积为研究对象,提出 了农作物种植面积指数模型(Pan-CPI模型)的概念,并构造了冬小麦特征物候期植被指数与种植面积的定量函数关系, 通过样区TM影像求解关键参数,对研究区冬小麦种植面积测量方法进行了试验研究。研究结果表明：(1)Pan-CPI模 型能够很好地反映特定目标农作物种植面积状况,为基于植被指数时间序列影像识别农作物种植面积提供了新方法; (2)精度分析结果表明：Pan-CPI模型具有很高的稳定性,且不受样本变化的影响,只要达到满足模型计算的样本量(如： 5%),多次测量结果间具有很好的一致性。选取MODIS 6×6像元大小的窗口时,TM样本的复相关系数(R2)稳定在0.85 左右,与TM结果比较,窗口相对精度稳定在95%左右,区域精度稳定在92%以上,经调整的区域精度高达96%以上; (3)对于种植结构复杂、目标作物种植破碎的地区,Pan-CPI模型可以充分利用MODIS植被指数时间序列的优势,有效改 善TM单时相和多时相提取信息因时相缺失无法表征作物变化的不足。     

Aridity changes in the Temperate-Mediterranean transition of the Andes since ad 1346 reconstructed from tree-rings

The Andes Cordillera acts as regional ??Water Towers?? for several countries and encompasses a wide range of ecosystems and climates. Several hydroclimatic changes have been described for portions of the Andes during recent years, including glacier retreat, negative precipitation trends, an elevation rise in the 0° isotherm, and changes in regional streamflow regimes. The Temperate-Mediterranean transition (TMT) zone of the Andes (35.5°?C39.5°S) is particularly at risk to climate change because it is a biodiversity hotspot with heavy human population pressure on water resources. In this paper we utilize a new tree-ring network of Austrocedrus chilensis to reconstruct past variations in regional moisture in the TMT of the Andes by means of the Palmer Drought Severity Index (PDSI). The reconstruction covers the past 657?years and captures interannual to decadal scales of variability in late spring?Cearly summer PDSI. These changes are related to the north?Csouth oscillations in moisture conditions between the Mediterranean and Temperate climates of the Andes as a consequence of the latitudinal position of the storm tracks forced by large-scale circulation modes. Kernel estimation of occurrence rates reveals an unprecedented increment of severe and extreme drought events during the last century in the context of the previous six centuries. Moisture conditions in our study region are linked to tropical and high-latitude ocean-atmospheric forcing, with PDSI positively related to Ni?o-3.4 SST during spring and strongly negatively correlated with the Antarctic Oscillation (AAO) during summer. Geopotential anomaly maps at 500-hPa show that extreme dry years are tightly associated with negative height anomalies in the Ross?CAmundsen Seas, in concordance with the strong negative relationship between PDSI and AAO. The twentieth century increase in extreme drought events in the TMT may not be related to ENSO but to the positive AAO trend during late-spring and summer resulting from a gradual poleward shift of the mid-latitude storm tracks. This first PDSI reconstruction for South America demonstrates the highly significant hindcast skill of A. chilensis as an aridity proxy.     

Meshless BEM and overlapping Schwarz preconditioners for exterior problems on spheroids

We consider the exterior Neumann problem of the Laplacian with boundary condition on spheroids. We propose to use spherical radial basis functions in the solution of the boundary integral equation arising from the Dirichlet-to-Neumann map. Our meshless approach with radial basis functions is particularly suitable for handling scattered satellite data. We also propose a preconditioning technique based on an overlapping domain decomposition method to deal with ill-conditioned matrices arising from the approximation problem.     

Environmental health impacts of mobility and transport in Hai Phong, Vietnam

Traffic is an essential part of modern society and mobility is part of its socio-economic setting. However, signs of counter productivity arise as the current mobility patterns substantially affect our health, including the consequences from traffic accidents, air pollution—which causes even more victims than traffic accidents—and traffic-noise. The use of private motorised vehicles also contributes to sedentarism, climate change and psychological effects. This paper reviews these mobility related health effects and applies them to the situation in Hai Phong, a Vietnamese port-city in fast development and facing growing mobility patterns. In his Master Plan the city developed a view on its development together with the transportation infrastructure up to 2020. Together with the fast changing mobility patterns, such as a modal change from bicycles to motorcycles and cars, this lead to an increase in motorized vehicles and non-negligible environmental health risks. Applying the methodology of a Health Impact Assessment as used in previous studies the current health burden is estimated, focussing on particulate matter (PM) and noise. For PM₁₀ 1287 deaths per year were calculated for the current situation, where the estimated number of deaths by 2020 doubled up to 2741. Hospital admissions due to PM₁₀ raised from 44,954 now to 51,467 in 2020 and for PM_2.5 the restricted-activity days were calculated, accounting for 852,352 per year. For noise only calculations for the current state (2007) were performed. The total estimated DALYs due to noise was 4758.     

Disaster risk reduction on non-sovereign islands: La Réunion and Mayotte,France

The Islands of Réunion and Mayotte are French territories in the Indian Ocean and are prone to numerous and recurrent hazards as well as to increasing vulnerabilities. This paper examines disaster risk reduction on non-sovereign islands through the case studies of Réunion and Mayotte. The approach used is embedded in standard geographical approaches to risk analysis, focusing on place-based vulnerability, in order to understand disaster risk and disaster risk reduction on both islands. In addition to establishing baseline information and visiting both islands for further data, 21 semi-structured individual interviews were completed to understand the people’s perceptions of the hazards and of their vulnerabilities. Disaster risk reduction strategies, and attitudes from governing bodies implementing the strategies, tend to assume similar vulnerability contexts as mainland France, despite obvious differences on the islands. Many policies are implemented in a top–down manner by those from mainland France who have little interest in, and who do not fully take into consideration, local realities. This paper contributes new case studies to the literature, especially in comparing two non-Anglophone non-sovereign islands, and reinforces recommendations factoring in local contexts when addressing ‘vulnerability of a place’ to disasters.     

Microstructure and hydraulic conductivity of a compacted lime-treated soil

Under a given compaction energy and procedure, it is known that maximum dry density of a soil is lowered due to lime addition. This modification of maximum dry density could alter the hydraulic conductivity of the soil. The main object of this study was to assess the impact of lime-stabilization on a silt soil microstructure and then on saturated hydraulic conductivity. An investigation at the microscopic level with mercury intrusion porosimetry showed that lime treatment induced the formation of a new small class, with a diameter lower than 3 × 10³ Å in the compacted soil. This class is responsible for the difference in dry density between the treated and the untreated sample after compaction. It is shown that this small pores class was not altered by the compaction water content, the compaction procedure or the dry density. As in untreated soils, only the larger pores were modified by the compaction water content and the compaction procedure in the lime treated samples. The hydraulic conductivity appeared to be only related to the largest pores volume of the tested silt, regardless of lime treatment. Therefore, this study demonstrated that even if addition of lime resulted in a dramatic change of the maximum dry density of the tested silty soil, its effect on hydraulic conductivity is limited.     

Analysis of the Excavation Deviations Impact on Geological Radioactive Waste Repository Performance

Numerical simulations of the transport of radionuclide from high-level radioactive waste stored in geological repositories often do not take into account construction defects in the repository. The potential impact of drilling and excavation deviation from the engineer planned design is a priori considered negligible. We conducted computations on repository geometries that contain deviations from horizontal of a few degrees. The analysis of the results shows that the impact of deviation defects varies from 9 to 16%. A perfect control of the galleries and waste repository cell orientations is then of concern for radioactive waste repository construction, failing which numerical simulations must be conducted on the worst geometric configuration or margin errors added. On the other hand, if the orientation control is precise enough, a modification of the repository design including controlled deviations from the horizontal may be of interest.