Pre-eruptive physical conditions of El Reventador volcano (Ecuador) inferred from the petrology of the 2002 and 2004–05 eruptions     

Pablo Samaniego  Jean-Philippe Eissen  Jean-Luc Le Pennec  Claude Robin  Minard L. Hall  Patricia Mothes  Deborah Chavrit  Joseph Cotten 《Journal of Volcanology and Geothermal Research》2008

A petrological study of the eruptive products of El Reventador allowed us to infer the magmatic processes related to the 2002 and 2004–05 eruptions of this andesitic stratovolcano. On November 3, 2002, El Reventador experienced a highly explosive event, which was followed by emplacement of two lava flows in November–December 2002. Silica contents range from 62 to 58 wt.% SiO₂ for the November 3 pyroclastic deposits to 58–56 and 54–53 wt.% SiO₂ for the successive lava flows. In November 2004 eruptive activity resumed supplying four new lava flows (56–54 wt.% SiO₂) between November 2004 and August 2005.  相似文献   

A nuanced quantile random forest approach for fast prediction of a stochastic marine flooding simulator applied to a macrotidal coastal site     

Jeremy Rohmer  Deborah Idier  Rodrigo Pedreros 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(6):867-890

Integrating full-process high resolution hydrodynamic simulations within early warning system (EWS) for marine flooding is hindered by the large computation time cost of such numerical models. This...  相似文献   

Characterization of site conditions (soil class,V<Subscript>S30</Subscript>, velocity profiles) for 33 stations from the French permanent accelerometric network (RAP) using surface-wave methods     

Fabrice Hollender  Cécile Cornou  Aline Dechamp  Kaveh Oghalaei  Florence Renalier  Emeline Maufroy  Clément Burnouf  Sylvette Thomassin  Marc Wathelet  Pierre-Yves Bard  Vincent Boutin  Clément Desbordes  Isabelle Douste-Bacqué  Laetitia Foundotos  Cédric Guyonnet-Benaize  Vincent Perron  Julie Régnier  Agathe Roullé  Mickael Langlais  Deborah Sicilia 《Bulletin of Earthquake Engineering》2018,16(6):2337-2365

Data provided by accelerometric networks are important for seismic hazard assessment. The correct use of accelerometric signals is conditioned by the station site metadata quality (i.e., soil class, V_S30, velocity profiles, and other relevant information that can help to quantify site effects). In France, the permanent accelerometric network consists of about 150 stations. Thirty-three of these stations in the southern half of France have been characterized, using surface-wave-based methods that allow derivation of velocity profiles from dispersion curves of surface waves. The computation of dispersion curves and their subsequent inversion in terms of shear-wave velocity profiles has allowed estimation of V_S30 values and designation of soil classes, which include the corresponding uncertainties. From a methodological point of view, this survey leads to the following recommendations: (1) perform both active (multi-analysis surface waves) and passive (ambient vibration arrays) measurements to derive dispersion curves in a broadband frequency range; (2) perform active acquisitions for both vertical (Rayleigh wave) and horizontal (Love wave) polarities. Even when the logistic contexts are sometimes difficult, the use of surface-wave-based methods is suitable for station-site characterization, even on rock sites. In comparison with previous studies that have mainly estimated V_S30 indirectly, the new values here are globally lower, but the EC8-A class sites remain numerous. However, even on rock sites, high frequency amplifications may affect accelerometric records, due to the shallow relatively softer layers.  相似文献   

Projected changes in flood indices in selected catchments in Poland in the 21st century     

Marzena?OsuchEmail author  Deborah?Lawrence  Hadush?K.?Meresa  Jaroslaw?J.?Napiorkowski  Renata?J.?Romanowicz 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(9):2435-2457

The aim of this study is to estimate likely changes in flood indices under a future climate and to assess the uncertainty in these estimates for selected catchments in Poland. Precipitation and temperature time series from climate simulations from the EURO-CORDEX initiative for the periods 1971–2000, 2021–2050 and 2071–2100 following the RCP4.5 and RCP8.5 emission scenarios have been used to produce hydrological simulations based on the HBV hydrological model. As the climate model outputs for Poland are highly biased, post processing in the form of bias correction was first performed so that the climate time series could be applied in hydrological simulations at a catchment-scale. The results indicate that bias correction significantly improves flow simulations and estimated flood indices based on comparisons with simulations from observed climate data for the control period. The estimated changes in the mean annual flood and in flood quantiles under a future climate indicate a large spread in the estimates both within and between the catchments. An ANOVA analysis was used to assess the relative contributions of the 2 emission scenarios, the 7 climate models and the 4 bias correction methods to the total spread in the projected changes in extreme river flow indices for each catchment. The analysis indicates that the differences between climate models generally make the largest contribution to the spread in the ensemble of the three factors considered. The results for bias corrected data show small differences between the four bias correction methods considered, and, in contrast with the results for uncorrected simulations, project increases in flood indices for most catchments under a future climate.  相似文献   

A temporal stable isotopic (δ18O, δD,d‐excess) comparison in glacier meltwater streams,Taylor Valley,Antarctica          下载免费PDF全文

Deborah L. Leslie  Kathleen A. Welch  W. Berry Lyons 《水文研究》2017,31(17):3069-3083

In this paper, we describe the importance of hyporheic dynamics within Andersen Creek and Von Guerard Stream, Taylor Valley, Antarctica, from the 2010–2011 melt season using natural tracers. Water collection started at flow onset and continued, with weekly hyporheic‐zone sampling. The water δ¹⁸O and δD values were isotopically lighter in the beginning and heavier later in the season. D‐excess measurements were used as an indicator of mixing because an evaporative signature was evident and distinguishable between 2 primary end‐members (glacier meltwater and hyporheic zone). Hyporheic‐zone influence on the channel water was variable with a strong control on streamwater chemistry, except at highest discharges. This work supports previous research indicating that Von Guerard Stream has a large, widespread hyporheic zone that varies in size with time and discharge. Andersen Creek, with a smaller hyporheic zone, displayed hyporheic‐zone solute interaction through the influence from subsurface hypersaline flow. Overall, the evolution of Taylor Valley hyporheic‐zone hydrology is described seasonally. In mid‐December, the hyporheic zone is a dynamic system exchanging with the glacier meltwater in the channel, and with diminishing flow in January, the hyporheic zone drains back into the channel flow also impacting stream chemistry. This work adds new information on the role of hyporheic zone–stream interaction in these glacier meltwater streams.  相似文献   

Transportation sustainability in the urban context: a comprehensive review     

Selima Sultana  Deborah Salon  Michael Kuby 《Urban geography》2019,40(3):279-308

ABSTRACT

Although the term “sustainability” did not gain traction until the 1980s, concerns about the consequences of transportation technology started long before. This paper reviews the literature on urban transportation sustainability using three frameworks. First, urban transportation can be unsustainable environmentally, economically, and socially (the three pillars of sustainability). Second, sustainable strategies tend to fall into two paradigms. Sustainable Transport Technology improves current patterns of modes and trips by consuming less resources and generating less waste. Sustainable Travel Behavior and Built Environment takes a more holistic approach that targets more sustainable travel choices, recognizing that changes in the built environment that currently constrains those choices are also essential. Third, the Planner’s Triangle helps explain commonly encountered situations where inherent tradeoffs can impede win-win-win strategies across environmental, economic, and social domains. The paper concludes with future research directions and concluding thoughts about urban transportation and sustainability.  相似文献   

Thresholds and relations for soil‐hydraulic and soil‐physical properties as a function of burn severity 4 years after the 2011 Las Conchas Fire,New Mexico,USA          下载免费PDF全文

Brian A. Ebel  Orlando C. Romero  Deborah A. Martin 《水文研究》2018,32(14):2263-2278

Wildfire effects on soil‐physical and ‐hydraulic properties as a function of burn severity are poorly characterized, especially several years after wildfire. A stratified random sampling approach was used in 2015 to sample seven sites representing a spectrum of remotely sensed burn severity in the area impacted by the 2011 Las Conchas Fire in New Mexico, USA. Replicate samples from each site were analysed in the laboratory. Linear and linear indicator regression were used to assess thresholds in soil‐physical and ‐hydraulic properties and functional relations with remotely sensed burn severity. Significant thresholds were present for initial soil‐water content (θ_i) at 0–6 cm depth between the change in the Normalized Burn Ratio (dNBR) equal to 618–802, for bulk density (ρ_b) at 3–6 cm between dNBR equal to 416–533, for gravel fraction at 0–1 cm between dNBR equal to 416–533, for fines (the silt + clay fraction) at 0–1 cm for dNBR equal to 416–533, and for fines at 3–6 cm for dNBR equal to 293–416. Significant linear relations with dNBR were present between ρ_b at 0–1 cm, loss on ignition (LOI) at 0–1 cm, gravel fraction at 0–1 cm, and the large organic fraction at 1–3 cm. No thresholds or effects on soil‐hydraulic properties of field‐saturated hydraulic conductivity or sorptivity were observed. These results suggest that ρ_b and LOI at 0–1 cm have residual direct impacts from the wildfire heat impulse. The θ_i threshold is most likely from delayed groundcover/vegetation recovery that increases evaporation at the highest burn severity sites. Gravel and silt + clay thresholds at 0–1 cm at the transition to high burn severity suggest surface gravel lag development from hydraulic erosion. Thresholds in ρ_b from 3 to 6 cm and in silt + clay fraction from 3 to 6 cm appear to be the result of soil variability between sites rather than wildfire impacts. This work suggests that gravel‐rich soils may have increased resilience to sustained surface runoff generation and erosion following wildfire, with implications for assessments of postwildfire hydrologic and erosion recovery potential.  相似文献   

Metabolic activity throughout early development of dusky kob Argyrosomus japonicus (Sciaenidae)     

C Edworthy  NC James  B Erasmus  JOG Kemp  H Kaiser  WM Potts 《African Journal of Marine Science》2018,40(1):67-74

The physiology of fishes in the early stages of development remains poorly assessed despite the importance of identifying energy bottlenecks in organisms faced with changing environmental conditions. This study describes the metabolic activity of dusky kob Argyrosomus japonicus throughout its early development, from hatchling to settlement stage. Standard, routine and active metabolic rates (SMR, RMR and AMR, respectively) were assessed to determine the species’ metabolic scope and identify how metabolism changes with growth and development. Distinct metabolic changes occurred in association with developmental changes during the early life stages, with flexion-stage larvae showing significantly reduced metabolic scope (approx. 0.30 µmol O₂ ind.^–1 h^–1), representing an energy bottleneck. Based on these findings, it is likely that larvae of A. japonicus are most susceptible to environmental perturbations during flexion. The variability of metabolic rates during the diel cycle was also assessed and revealed that the early-stage larvae showed no preference for daylight, although settlement-stage juveniles were more active during daylight hours (RMR = 12.78 µmol O₂ ind.^–1 h^–1) than at night (RMR = 5.87 µmol O₂ ind.^–1 h^–1). These results suggest that metabolic measurements of the SMR of A. japonicus larvae can be taken at any time of the diel cycle until the settlement phase, when readings should take place at night.  相似文献   

The Dramas of the Marine Extractive Reserve Managers in Brazil: Navigating through Multiple Institutions     

Deborah Santos Prado  Fábio de Castro  Cristiana Simão Seixas 《社会与自然资源》2020,33(5):651-668

Abstract

In this paper, we describe and analyze the co-management institutional framework at 21 Brazilian Marine Extractive Reserves (MERs) and present the dramas of its implementation from the local manager’s perspective. We categorized the governance instruments of MERs into (i) instruments for land/sea tenure and beneficiaries’ recognition, (ii) territorial use planning, (iii) institutional arenas for discussion and deliberation, as well as (iv) public policies. Although the legal arrangements of these protected areas address fundamental dimensions of governance, we present the challenges of its implementation based on the voice of local managers. The managers are the bridge between the central government and communities, dealing with the implementation of the institutional framework in a reality of multi-level and multi-scale drama: from local to national dilemmas, from organizational to structural ones. We explore these dramas and highlight the institutional dilemmas based on the paradoxes between legalism and social emancipation.  相似文献   

Blast‐induced rock fracture near a tunnel          下载免费PDF全文

Ling Xu  Howard Schreyer  Deborah Sulsky 《国际地质力学数值与分析法杂志》2015,39(1):23-50

Damage in the form of cracks is predicted to assess the susceptibility of a tunnel to failure due to a blast. The material‐point method is used in conjunction with a decohesive failure model as the basis for the numerical simulations. The assumption of a cylindrical charge as the source for the blast allows the restriction of plane strain and two‐dimensional analyses. In the simulation, a further restriction of a single pressure pulse is used as the source of stress waves that are reflected and refracted after reaching the free surface of the tunnel wall. Three critical zones of significant cracking in the vicinity of a tunnel are identified as potential contributors to tunnel failure. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献