地震能够应力预测

1997年Geller等人曾发表"地震不能预报",因为在自组织临界系统中尺度不变性是普遍存在的,而地球正处于自组织临界状态中,在这种状态下小地震具有某种概率,如瀑布般触发大的地震事件。但是在物理上,只有对应其地震震级的应力能量得到有效释放,才能有大地震的发生。利用对这种应力的依赖性可以进行地震预测,方法就是利用剪切波分裂来监控即将发生地震的周围岩体的应力积累。这项技术可以说是成功的,但是由于假定的不可预报性,所以需要清晰的论证才能被普遍接受。雪崩也是自组织临界现象。近期通过二维球形素珠堆进行的雪崩实验观测表明,具有自组织临界性的自然物理现象是能够预报的,如雪崩、地震等。预报地震和雪崩的关键是监控母体介质,而不是即将发震的震源区。     

The role of soil in vegetated gravelly river braid plains: more than just a passive response?

This paper reviews the role of alluvial soils in vegetated gravelly river braid plains. When considering decadal timescales of river evolution, we argue that it becomes vital to consider soil development as an emergent property of the developing ecosystem. Soil processes have been relatively overlooked in accounts of the interactions between braided river processes and vegetation, although soils have been observed on vegetated fluvial landforms. We hypothesize that soil development plays a major role in the transition (speed and pathway) from a fresh sediment deposit to a vegetated soil‐covered landform. Disturbance (erosion and/or deposition), vertical sediment structure (process history), vegetation succession, biological activity and water table fluctuation are seen as the main controls on early alluvial soil evolution. Erosion and deposition processes may not only act as soil disturbing agents, but also as suppliers of ecosystem resources, because of their role in delivering and changing access (e.g. through avulsion) to fluxes of water, fine sediments and organic matter. In turn, the associated initial ecosystem may influence further fluvial landform development, such as through the trapping of fine‐grained sediments (e.g. sand) by the engineering action of vegetation and the deposit stabilization by the developing aboveground and belowground biomass. This may create a strong feedback between geomorphological processes, vegetation succession and soil evolution which we summarize in a conceptual model. We illustrate this model by an example from the Allondon River (Switzerland) and identify the research questions that follow. Copyright © 2014 John Wiley & Sons, Ltd.     

Investigating the geomorphological potential of freely available and accessible structure‐from‐motion photogrammetry using a smartphone

We test the acquisition of high‐resolution topographic and terrain data using hand‐held smartphone technology, where the acquired images can be processed using technology freely available to the research community. This is achieved by evaluating the quality of digital terrain models (DTM) of a river bank and an Alpine alluvial fan generated with a fully automated, free‐to‐use, structure‐from‐motion package and a smartphone integrated camera (5 megapixels) with terrestrial laser scanning (TLS) data used to provide a benchmark. To evaluate this approach a 16.2‐megapixel digital camera and an established, commercial, close‐range and semi‐automated software are also employed, and the product of the four combinations of the two types of cameras and software are compared. Results for the river bank survey demonstrate that centimetre‐precision DTMs can be achieved at close range (10 m or less), using a smartphone camera and a fully automated package. Results improve to sub‐centimetre precision with either higher‐resolution images or by applying specific post‐processing techniques to the smartphone DTMs. Application to an entire Alpine alluvial fan system shows the degradation of precision scales linearly with image scale, but that (i) the expected level of precision remains and (ii) difficulties in separating vegetation and sediment cover within the results are similar to those typically found when using other photo‐based techniques and laser scanning systems. Copyright © 2014 John Wiley & Sons, Ltd.     

Globalising New Zealand : Fonterra Co-operative Group, and shaping the future

New Zealanders have little collective vision of their position and future in a globalising world. Recent developments in New Zealand's primary sector show potential pathways to the future. We explore two claims: thinking about New Zealand is to think about the emergence of Fonterra Co-operative Group in New Zealand's globalising economy. Thinking about Fonterra is to think about New Zealand and the implications that spring from globalising activities. Fonterra is a lens to understand better the possibilities and development options and the challenges that are arising as New Zealand forges its place in a globalising world.     

Spinning particles in Saturn's C ring from mid-infrared observations: Pre-Cassini mission results

Saturn's C ring thermal emission has been observed in mid-infrared wavelengths, at three different epochs and solar phase angles, using ground based instruments (CFHT in 1999 and VLT/ESO in 2005) and the Infrared Radiometer Instrument Spectrometer (IRIS) onboard the Voyager 1 spacecraft in 1980. Azimuthal variations of temperature in the C ring's inner region, observed at several phase angles, have been analyzed using our new standard thermal model [Ferrari, C., Leyrat, C., 2006. Astron. Astrophys. 447, 745-760]. This model provides predicted ring temperatures for a monolayer ring composed of spinning icy spherical particles. We confirm the very low thermal inertia (on the order of 10 ) found previously by Ferrari et al. [Ferrari, C., Galdemard, P., Lagage, P.O., Pantin E., Quoirin, C., 2005. Astron. Astrophys. 441, 379-389] that reveals the very porous regolith at the surface of ring particles. We are able to explain both azimuthal variations of temperature and the strong asymmetry of the emission function between low and high phase angles. We show that large particles spinning almost synchronously might be present in the C ring to explain differences of temperature observed between low and high phase angle. Their cross section might represent about 45% of the total cross section. However, their numerical fraction is estimated to only ∼0.1% of all particles. Thermal behavior of other particles can be modeled as isothermal behavior. This work provides an indirect estimation of the particle's rotation rate in Saturn's rings from observations.     

Infrared observations of Saturn's rings by Cassini CIRS : Phase angle and local time dependence

Since the Saturn orbit insertion (SOI) of the Cassini spacecraft, in July 2004, the Cassini Composite Infrared Spectrometer (CIRS) has obtained a large number of thermal infrared spectra of Saturn's rings. Over the two and a half years of observations to date, ring temperatures were retrieved for a large range of unique geometries, inaccessible from Earth. Understanding their dependencies with phase angle and local time is a clue to understanding the thermal properties and dynamics of Saturn's ring particles.Azimuthal scans of rings, which have been obtained by CIRS at constant radial distance from the planet, have been planned to measure ring temperature variations with local hour angle. Over 47 azimuthal scans for Saturn's main rings (A, B, C and Cassini Division) have been retrieved to date, on both lit and unlit sides, at different phase angles and spacecraft elevations. The first measurements of the transient thermal episode of eclipse cooling in the planetary shadow have also been obtained for all three rings.In this paper, we present an overview of all azimuthal scans obtained by the Cassini/CIRS instrument so far and the dependencies of the temperature and the filling factor with the phase angle and the local hour angle. The ring temperature varies with longitude as the input heating flux coming from Saturn and the Sun changes. The decrease in temperature with the increasing phase angle on both the lit and the unlit sides and for most of the local time also suggests the presence of slowly rotating particles. The crossing of the planet's shadow generates drastic azimuthal variations in temperature, up to 20 K in the C ring. The strong anisotropy of emission observed outside the shadow between low and high phase angles decreases when ring particles cross the shadow, suggesting that particles are almost isothermal in the shadow. This suggests a thermal inertia associated with a rotating rate of particles low enough to have a thermal contrast on their surface.The temperature in the B ring is less sensitive to the phase angle effect on the lit side, suggesting that particles are close enough to form a flat layer at a scale larger than the particle's radius. On the unlit side, particles in the B ring are less sensitive to the lack of solar input than in the C ring or in the A ring. Azimuthal variations of the filling factor in the A ring are also detected with changing ring local time. This effect might be created by the presence of gravitational instabilities (wakes).     

Double-averaged velocity and stress distributions for hydraulically-smooth and transitionally-rough turbulent flows

We analyse experimental measurements of turbulent open-channel flow over hydraulically-smooth and transitionally-rough beds using the double-averaging methodology. Oil with a viscosity of 15×10^?6 m2/s is used instead of water so that transitional-range roughness Reynolds numbers can be achieved with large (11.1 mm) roughness elements, allowing spatial variations in the mean velocity field to more easily be measured. Distributions of double-averaged velocities, turbulence intensities, form-induced intensities, and viscous, Reynolds, form-induced and total shear stresses are studied with comparisons made between distributions for hydraulically-smooth, transitionally-rough, and fully-rough boundaries. Measured streamwise turbulence intensities for all experiments peaked at a constant distance from the bed (z ⁺+d ⁺ = 15) when elevation scale is adjusted using the zero-plane displacement d for the logarithmic velocity distribution. This collapse suggests that turbulence intensity distributions may be useful in assessing appropriate values of d for transitionally-rough and fully-rough boundaries. Form-induced normal and shear stresses above the roughness tops were found to collapse towards a common curve independent of roughness Reynolds number.     

A Tsunami Detection and Warning-focused Sea Level Station Metadata Web Service

Currently information used to describe sea-level stations (such as location, collection and transmission capabilities, operator identification, etc.) is distributed among databases held by multiple agencies, institutions and organizations. Such information could be used to support detection and warning. However, the Indian Ocean Tsunami of 26 December, 2004 made it clear that such information is not readily accessible, is difficult to use, and is often incomplete. In addressing this issue, agencies within the Pacific region are collaborating to develop a web service to expose station metadata enabling various types of real-time data mining client applications that support decision-making and strategic planning at Tsunami Warning Centers. Because information about sea levels has a broad range of applications, integration of this information in a way that is comprehensive, and enhances its access and use, would have a tremendous impact on lives and livelihoods.     

Milankovitch forcing of bioturbation intensity in deep-marine thin-bedded siliciclastic turbidites

Trace fossils have been used to infer a Milankovitch-type control on pelagic and hemipelagic sediments, but there have been no comparable studies in deep-marine siliciclastic turbidite successions. Here, we present the results of a quantitative analysis of trace-fossil abundance and intensity in an essentially continuous, Middle Eocene, 230-m-long (Well A6) core, comprising very thin- and thin-bedded siliciclastic turbidites in the deep-marine Ainsa basin, Spanish Pyrenees. After removing the sediment slides and debris flow deposits, as these represent geologically instantaneous events approximately two orders of magnitude thicker than the typical laminated turbiditic sediments in the core, spectral analysis was conducted on the bioturbation intensity data. Spectral analysis of bioturbation intensity in the A6 core suggests, for the first time from a siliciclastic turbidite succession at a tectonically active plate margin (thrust-top basin in a foreland basin), a cyclicity that is interpreted to reflect the 41-kyr and an ~ 112-kyr (possibly an average of the 95- and 125-kyr) Milankovitch frequencies. We propose that this drove environmental changes in bottom-water conditions in the Ainsa basin, most likely leading to critically varying levels of oxygenation (stratification) of bottom waters. Our age model for the Ainsa basin (~ 4 km of deep-marine sediments in ~ 10 Myr) yields an average sediment accumulation rate of ~ 40 cm kyr^− 1, that is consistent with that inferred from the spectral analysis (~ 30 cm kyr^− 1) for fine-grained sedimentation. An implication of these results is that global environmental change, probably glacio-eustasy, acted as a driver on deep-marine siliciclastic sedimentation patterns during the Middle Eocene.