Adjustability of exposed elements by updating their capacity for resistance after a damaging event: application to an earthquake–tsunami cascade scenario     

Negulescu  Caterina  Benaïchouche  Abed  Lemoine  Anne  Le Roy  Sylvestre  Pedreros  Rodrigo 《Natural Hazards》2020,104(1):753-793

Natural Hazards - The 2011 Great East Japan earthquake and tsunami remind us once again that these types of cascade event can occur and cause considerable damage. The scientific community realizes...  相似文献   

Evolution and sedimentology of a channel fill in the sandy braided South Saskatchewan River and its comparison to the deposits of an adjacent compound bar     

PHILIP J. ASHWORTH  GREGORY H. SAMBROOK SMITH  JAMES L. BEST  JOHN S. BRIDGE  STUART N. LANE  IAN. A. LUNT  ARNOLD J. H. REESINK  CHRISTOPHER J. SIMPSON  ROBERT E. THOMAS 《Sedimentology》2011,58(7):1860-1883

The depositional stratigraphy of within‐channel deposits in sandy braided rivers is dominated by a variety of barforms (both singular ‘unit’ bars and complex ‘compound’ bars), as well as the infill of individual channels (herein termed ‘channel fills’). The deposits of bars and channel fills define the key components of facies models for braided rivers and their within‐channel heterogeneity, knowledge of which is important for reservoir characterization. However, few studies have sought to address the question of whether the deposits of bars and channel fills can be readily differentiated from each other. This paper presents the first quantitative study to achieve this aim, using aerial images of an evolving modern sandy braided river and geophysical imaging of its subsurface deposits. Aerial photographs taken between 2000 and 2004 document the abandonment and fill of a 1·3 km long, 80 m wide anabranch channel in the sandy braided South Saskatchewan River, Canada. Upstream river regulation traps the majority of very fine sediment and there is little clay (< 1%) in the bed sediments. Channel abandonment was initiated by a series of unit bars that stalled and progressively blocked the anabranch entrance, together with dune deposition and stacking at the anabranch entrance and exit. Complete channel abandonment and subsequent fill of up to 3 m of sediment took approximately two years. Thirteen kilometres of ground‐penetrating radar surveys, coupled with 18 cores, were obtained over the channel fill and an adjacent 750 m long, 400 m wide, compound bar, enabling a quantitative analysis of the channel and bar deposits. Results show that, in terms of grain‐size trends, facies proportions and scale of deposits, there are only subtle differences between the channel fill and bar deposits which, therefore, renders them indistinguishable. Thus, it may be inappropriate to assign different geometric and sedimentological attributes to channel fill and bar facies in object‐based models of sandy braided river alluvial architecture.  相似文献   

SPATIAL AND THERMAL CHARACTERISTICS OF MOUNTAIN PERMAFROST,NORTHWEST CANADA     

ANTONI G. LEWKOWICZ  PHILIP P. BONNAVENTURE  SHARON L. SMITH  ZOÉ KUNTZ 《Geografiska Annaler: Series A, Physical Geography》2012,94(2):195-213

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The place of rural, remote and least-wealthy small islands in international water development: the nexus of geography–technology sustainability in Chuuk State, Federated States of Micronesia     

WILLIAM JAMES SMITH JR 《The Geographical journal》2008,174(3):251-268

Many least-wealthy, rural, remote and resource-poor small island communities are unlikely to benefit from high-profile global water improvement initiatives. Their small landmasses, geologic composition, geography, social and technological isolation, colonial history, and weak educational and financial resources constitute significant barriers to improving access to safe drinking water. This paper discusses the relatively unique position of such island societies in the international community, providing a case study of the Federated States of Micronesia that integrates data and information pertaining to water resources management and governance, spanning from the island village to national scale. A vision is offered regarding the interaction between small island human and biophysical water systems, manifesting ways to pursue water resource development to improve public health which are constructed to be economically, physically and culturally sustainable.  相似文献   

Fossils explained 3: Sea urchins     

ANDREW B. SMITH 《Geology Today》1985,1(5):150-151

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Water vapour ¹⁸O/¹⁶O isotope ratio in surface air in New England, USA     

XUHUI LEE  RONALD SMITH  JOHN WILLIAMS 《Tellus. Series B, Chemical and physical meteorology》2006,58(4):293-304

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The role of the microbial loop in Antarctic pelagic ecosystems     

FAROOQ AZAM  DAVID C. SMITH  JAMES T. HOLLIBAUGH 《Polar research》1991,10(1):239-244

The Paradigm pelagic food web organization in Antarctic waters is undergoing fundamental revision evidence that large fractions of material and energy flow through the microbial food web. because of the unique Antarctic ecosystem conditions, the microbial food web performs some roles that are fundamentally different from those in oligotrophic temperate and tropical waters: 1) during winter, bacterial production, at the expense of slow-turnover DOM (dissolved organic matter) from the previous summer, could be a significant factor in the survival of over wintering animal populations; 2) microbial regeneration of ammonium in nitrate-replete Antarctic waters may spare the reductants necessary for nitrate assimilation and thus enhance primary productivity of deep-mixed light-limited phytoplankton; and 3) the small diatoms and phytoflagellates which dominate the Antarctic pelagic primary production are apparently directly digestible by the metazoan herbivores, whereas cyanobacteria which dominate the primary productivity in lower latitude oligotrophic waters are not digestible by the metazoan herbivores. These roles performed by the microbial loop may, in part, explain why Antarctic waters, in contrast to the lower latitude oligotrophic waters, have high levels of tertiary productivity despite low primary productivity.  相似文献   

Redistriution of Major Elements in the Alteration of Some Basic Lavas during Burial Metamorphism     

SMITH  R. E. 《Journal of Petrology》1968,9(2):191-219

An Ordovician geanticlinal marine sequence is exposed in theCentral West of New South Wales, Australia. The sequence containingbasic lavas, labile sedimentary, and proclastic rocks, has undergoneextensive adjustment during regional burial metamorphism. Thebasic lavas have a patchy coloration due to the formation ofalternation minerals of the prehnite-pumpellyite facies whichapperar to have formed during the metamorphism. The hererogeneousappearance of the basic lavas reflects a pronouced chemicaland mineralogical departure from the original composition. Twodiverging trends result. One leads to the production of a Ca-enrichedlithology, the other, which by far dominates in area at eachouterop, leads to a ‘spilitic’ lithology. The alterationdomains in many cases cross–cut all primary textural featureand their chemical variation does not correspond to likely variationsin the original lava composition.  相似文献   

Compositional Zoning in Pyroxenes from Lunar Rock 12021, Oceanus Procellarum     

BOYD  F. R.; SMITH  DOUGLAS 《Journal of Petrology》1971,12(3):439-464

Electron probe study of the pyroxene phenocrysts in rock 12021of the Apollo 12 sample reveals an extraordinary variety ofzoning phenomena. These phenocrysts have cores of relativelyhomogeneous pigeonite which are mantled by Ca-rich pyroxenes;the mantles are zoned outward from about 20 mol per cent FeSiO₃at the core-mantle boundaries to 70 mol per cent FeSiO₃ at themargins of the phenocrysts. The character of the normal zoningdiffers in each growth sector. Four different trends characterizinggrowth on (110), (100), (010), and parallel to c are described.Pronounced but erratic oscillatory effects are impressed onthe normal zoning in all sectors. Normal zoning in lunar pyroxenes is generally more extensivethan in terrestrial pyroxenes, probably because the lunar lavaswere an order of magnitude more fluid than terrestrial basalts.Turbulent flow in lunar lavas may have caused some of the oscillatoryeffects. The cyclic nature of augite and pigeonite crystallizationin these pyroxenes is probably kinetic in origin; conceivablyit could reflect the presence of an augite-pigeonite peritectic.It is likely that further knowledge of the crystal structureof pigeonite at high temperatures will be required before astructural model can be formulated that will satisfactorilyexplain the details of the sector zoning. Coarse-grained pyroxferroite and subcalcic ferroaugite havecrystallized in apparent ‘equilibrium’ in the finalstages of formation of the groundmass in rock 12021. Nevertheless,the crystallization of the pyroxferroite was probably metastablerelative to the assemblage ferroaugite+ fayalite+ tridymite.Data on the effect of Mg substitution on the stability of pyroxferroitewill be needed to establish this point. We suggest that the pigeonite cores of the phenocrysts in rock12021 crystallized under quiescent conditions, probably in amagma chamber below the lunar surface, and that the stronglyzoned augite mantles crystallized during emplacement of thelava on the surface.  相似文献   

Degradation and Metamorphic Differentiation of the Keweenawan Tholeiitic Lavas of Northern Michigan, U.S.A.     

JOLLY  WAYNE T.; SMITH  RAYMOND E. 《Journal of Petrology》1972,13(2):273-309

The Portage Lake Lava Series of the Keweenaw Peninsula, northernMichigan, is composed of over 5000 m of tholeiitic lava flows.Chemical and petrologic study of thin undifferentiated flowsfrom this sequence shows that the bulk of the flows are olivinetholeiites; highly ironenriched tholeiites comprise up to 10per cent of the volume. In addition, a few small rhyolitic intrusives,exceedingly rich in alkalis, are exposed in the region. Duringburial the amygdular tops of each flow acted as channelwaysfor migrating fluids during a regional metamorphic event thatproduced a progressive sequence of secondary phases within theflow tops. In the upper part of the stratigraphic section, laumontite,analcime, albite, and chlorite dominate assemblages characteristicof the zeolite facies. Stratigraphically deeper. flow tops arecharacterized by metamorphic assemblages of the prehnite-pumpellyitefacies. Within the higher rank facies, rocks along fractureshave been transformed to calcium-rich monomineralic domains(metadomains) of epidote or pumpellyite. These metadomains gradeoutward through incompletely reconstituted rocks containingalbitized feldspars, and finally, in flow centers, to basaltdisplaying few signs of mineralogical readjustment. Extremechemical disparity exists within the altered flow tops, particularlywith respect to calcium and sodium content. Calculations revealthat bulk compositions of metamorphically adjusted flow topsare similar to unaltered basalts. Thus, the chemical variationdisplayed by the metamorphic rock types resulted from localizedmetamorphic differentiation. The Keweenawan sequence displays progressive dehydration fromthe top to the base of the stratigraphic section. At the topchlorite (H₂O = 12 per cent) and pumpellyite (H₂O = 6 per cent)metadomains formed by dehydration. The fact that most of theserocks were hydrated strongly suggests that fluid pressures wereless than total pressures during the metamorphic event. In rocksundergoing hydration in the uper part of the stratigraphic section,therefore, water pressures decreased away from channelways.As a result, the most hydrous rock types formed in these regions.Conversely, in rock undergoing dehydration water pressures increasedaway from channelwasys, so that the most dehydrated rocks formedin such regions. Water content of an individual rock is dependenton both position in the stratigraphic pile and position withrespect to fluid channelways.  相似文献