Adoption of flood-related preventive behaviours by people having different risks and histories of flooding

Natural Hazards - The increase in the frequency of floods, which is a projected consequence of climate change, can have wide-ranging health and economic impacts. To cope with these floods and to...     

Resorption process in Astypalaea Linea extensive region (Europa)

Whereas numerous extensive features, where new crust is created, are now well recognized on Europa's surface, those relevant to crust disappearance remain difficult to find. This work presents a reconstruction of the surface prior to Astypalaea Linea's emplacement (one of the features where new crustal material appears). We demonstrate that a scattered disappearance of crust takes place in an extensive region close to Astypalaea Linea. Physical processes invoked for disappearance are discussed: pressure melting may be responsible for the mobilization of surface material and its collapse down through the icy crust.     

Amphibole—Bearing Peridotite Xenoliths from Nushan,Anhui Province：Evidence for Melt Percolation Process in the Upper mantle and Lithospheric uplift

The spinel peridotite xenoliths of Group I in Quaternary basanites from Nushan,Anhui province,can be classified as two suites:a hydrous suite characterized by the ubiquitous occurrence of (Ti-) pargasite and an anhydrous suite.The nineral chemistry reveals that the anhydrous suite and one associated phlogopite-bearing lherzolite are equilibrated under temperature conditions of 1000-1100℃,whereas amplhibole-bearing peridotites display distinct disequilibrum features,indicating partial reequilibration from 1050 to 850℃ and locally down to 750℃. The amplhbole-bearing peridotites were probably the uppermost part of the high temperature anhydrous suite which was modally modifed by fractionating H2O-rich metasomatic agent during regional upwelling.This relatively recent lithospheric uplift event followed an older uplift event recognized from pyroxene unmixing of domains in local equilibrium,as well as the dominant deformation texture in the anhydrous suite.The first thermal disturbance can be linked with the regional extension and widespread basaltic volcanism in Jiangsu-Anhui provinces since Early Tertiary and the formation of the nearby Subei(North Jiangsu) fault-depression basin during the Eocene,while the second event in association with the formation of amphiboles probably indicates the continuation but diminution of upwared mantle flux since Neogene in response to the change in tectonic regime for eastern china.     

Observations of atmospheric gravity waves by radio interferometry: are results biased by the observational technique?

In this paper we present a quantitative comparison between a large data base of medium-scale atmospheric gravity waves (AGWs) observed by radio interferometry of transionospheric radio sources and the results of a numerical simulation of the observed effects. The simulation includes: (i) the propagation and dissipation of AGWs up to ionospheric heights and (ii) the calculation of the subsequent slant TEC perturbations integrated along the path to the radio sources. We show that the observed azimuthal distribution of AGWs can be deeply biased. Predicted results are found to be consistent with previous extensive observations using radio beacons aboard geostationary satellites. These observations are rediscussed in view of the present predictions.     

From oblique subduction to intra-continental transpression: Structures of the southern Kermadec-Hikurangi margin from multibeam bathymetry,side-scan sonar and seismic reflection

The southern Kermadec-Hikurangi convergent margin, east of New Zealand, accommodates the oblique subduction of the oceanic Hikurangi Plateau at rates of 4–5 cm/yr. Swath bathymetry and sidescan data, together with seismic reflection and geopotential data obtained during the GEODYNZ-SUD cruise, showed major changes in tectonic style along the margin. The changes reflect the size and abundance of seamounts on the subducting plateau, the presence and thickness of trench-fill turbidites, and the change to increasing obliquity and intracontinental transpression towards the south. In this paper, we provide evidence that faulting with a significant strike-slip component is widespread along the entire 1000 km margin. Subduction of the northeastern scrap of the Hikurangi Plateau is marked by an offset in the Kermadec Trench and adjacent margin, and by a major NW-trending tear fault in the scarp. To the south, the southern Kermadec Trench is devoid of turbidite fill and the adjacent margin is characterized by an up to 1200 m high scarp that locally separates apparent clockwise rotated blocks on the upper slope from strike-slip faults and mass wasting on the lower slope. The northern Hikurangi Trough has at least 1 km of trench-fill but its adjacent margin is characterized by tectonic erosion. The toe of the margin is indented by 10–25 km for more than 200 km, and this is inferred to be the result of repeated impacts of the large seamounts that are abundant on the northern Hikurangi Plateau. The two most recent impacts have left major indentations in the margin. The central Hikurangi margin is characterized by development of a wide accretionary wedge on the lower slope, and by transpression of presubduction passive margin sediments on the upper slope. Shortening across the wedge together with a component of strike-slip motion on the upper slope supports an interpretation of some strain partitioning. The southern Hikurangi margin is a narrow, mainly compressive belt along a very oblique, apparently locked subduction zone.     

The mark II Nançay radioheliograph

We describe the new Nançay Radioheliograph (version II) which is a multicorrelator system. The main characteristics of this instrument are high space and time resolutions and flexible on-line data processing. At present it produces one-dimensional images at 169 MHz. This instrument is mainly intended for solar observations.An accurate calibration of the instrument has been carried out leading to a precise fringe stopping and to a proper knowledge of the grating response. Preliminary solar results are presented: existence of apparent motions in noise storms with a velocity of the order of 5000 km s^–1; observations of radiobursts as narrow as 0.7 (Kerdraon, 1977); observations of spikeburst activity.Presently in Sydney, Australia.     

Teleseismic waveform modelling with a one-way wave equation

It is now widely accepted that elastic properties of the continental lithosphere and the underlying sublithospheric mantle are both anisotropic and laterally heterogeneous at a range of scales. To fully exploit modern three-component broad-band array data sets requires the use of comprehensive modelling tools. In this work, we investigate the use of a wide-angle, one-way wave equation to model variations in teleseismic 3-D waveforms due to 2-D elastic heterogeneity and anisotropy. The one-way operators are derived based on a high-frequency approximation of the square-root operator and include the effects of wave propagation as well as multiple scattering. Computational cost is reduced through a number of physically motivated approximations. We present synthetic results from simple 1-D (layer over a half-space) and 2-D (subduction zone) models that are compared with reference solutions. The algorithm is then used to model data from an array of broad-band seismograph stations deployed in northwestern Canada as part of the IRIS-PASSCAL/LITHOPROBE CANOE experiment. In this region radial-component receiver functions show a clear continental Moho and the presence of crustal material dipping into the mantle at the suture of two Palaeo-Proterozoic terranes. The geometry of the suture is better defined on the transverse component where subduction is associated with a ∼10 km thick layer exhibiting strong elastic anisotropy. The modelling reproduces the main features of the receiver functions, including the effects of anisotropy, heterogeneity and finite-frequency scattering.     

熔体─上地幔岩石的相互作用及稀土元素模拟计算──以法国中央高原堡雷(Bore)幔源包体为例

产于法国中央高原堡雷（Boree）的具镶嵌结构方辉橄榄岩包体被认为是大陆活动区碱性玄武岩捕获的、来源最深的尖晶石相上地幔样品。已有的岩浆堆积说和等物理化学环境中重结晶模式难于解释其矿物学、微量元素和Sr－Nd同位素地球化学特征,为此我们提出了热柱来源熔体渗滤岩石圈底部的新成因模式。渗滤熔体和岩石圈地幔之间的反应不仅导致了矿物含量的变化,而且形成了特征的微量元素配分型式和同位素组成。REE模拟计算表明,熔体／岩石比值的大小、熔体性质以及熔体-岩石反应机制的多样性是控制本区幔源包体地球化学及其岩石变形、结晶程度之间相关性的重要因素。     

Recent climatic trends and linkages to river discharge in Central Vietnam

In this study, change in rainfall, temperature and river discharge are analysed over the last three decades in Central Vietnam. Trends and rainfall indices are evaluated using non‐parametric tests at different temporal levels. To overcome the sparse locally available network, the high resolution APHRODITE gridded dataset is used in addition to the existing rain gauges. Finally, existing linkages between discharge changes and trends in rainfall and temperature are explored. Results are indicative of an intensification of rainfall (+15%/decade), with more extreme and longer events. A significant increase in winter rainfall and a decrease in consecutive dry days provides strong evidence for a lengthening wet season in Central Vietnam. In addition, trends based on APHRODITE suggest a strong orographic signal in winter and annual trends. These results underline the local variability in the impacts of climatic change at the global scale. Consequently, it is important that change detection investigations are conducted at the local scale. A very weak signal is detected in the trend of minimum temperature (+0.2°C/decade). River discharge trends show an increase in mean discharge (31 to 35%/decade) over the last decades. Between 54 and 74% of this increase is explained by the increase in precipitation. The maximum discharge also responds significantly to precipitation changes leading to a lengthened wet season and an increase in extreme rainfall events. Such trends can be linked with a likely increase in floods in Central Vietnam, which is important for future adaptation planning and management and flood preparedness in the region. Copyright © 2012 John Wiley & Sons, Ltd.