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A system of numerical tools to predict the non-local long-term impact of large-scale constructions on the environment is described. The predictions have to be results of successive examination of free water oscillations, turbulent boundary layers on the sea bottom, and turbulent pulsation effects on sediment transport. Numerical results related to free water oscillations in diverse gulfs are shown, and non-local effects of the dam construction are found for an example of the Baltic Sea. Feasibility of suggested tools for turbulent flow is manifested. 相似文献
23.
Co-seismic phenomena along the south coastline included liquefaction, subsidenceand tsunami. Construction on areas composed of fluvial and alluvial sediments aswell as unconsolidated fill increased the risk by creating potential for amplificationof seismic waves. Cyclic mobility liquefaction was common along the coastline, andlevel-ground liquefaction was observed. Flow liquefaction is held forth as a possibilityin the Deirmendere submarine landslide. Damage to structures was markedly more in areas of unconsolidated sediments. One or more tsunami struck immediately after the event; the uniformity of tsunami impact indicating a wave coming from 310° suggests that submarine faulting was the major source of tsunami. Over 800,000 m2 of subsidence resulted from sediment slumping, fault controlled subsidence, and possibly post-liquefaction sediment compaction. After a brief period of post-event abandonment, reclamation and use of coastal areas is well underway. This creates a tension between human desires pushing for quick and inexpensive re-inhabitation of the coastal areas, and the needs for zoning and building codes for risk reduction. In this high-risk area suchcontrary cultural mandates cannot yield ideal results. It is suggested that an alternativemodel of immediate post-event creation of parks and natural areas that would yield benefit is preferable in coastal areas rather than the enforcement approach currently favored. 相似文献
24.
The orbital evolution of model meteoroids ejected from the comet Encke has been investigated. The particles abandon the mother body with velocities 20 and 40 ms-1 perihelion within the interval of the past 10,000 years. Their 10,000 years old osculating orbits were numerically integrated forward, using a dynamical model of the solar system consisting of all planets. Forces from solar electromagnetic and corpuscular radiation effecting the particles are considered, too. Orbital dispersions of the model meteoroids are presented. The importance of nongravitational forces for a long-term orbital evolution of meteoroid streams is shown. 相似文献
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Eduard Koa 《Marine and Petroleum Geology》2007,24(10):632-652
Deep-water Palaeocene strata of the East Central Graben, UK North Sea, are characterised by elongate depressions and elevations parallel with the palaeotransport direction and with underlying structural lineaments. Palaeozoic and mesozoic faults underlying the basin were briefly re-activated during the Palaeocene, affecting the seabed topography in the form of gentle folding, faulting and slope instability. Two types of mounded features formed in response to the tectonically induced seabed structuration: (i) deformational mounded morphology, a product of syndepositional faulting and mass wasting, (ii) non-deformational mounded morphology, interpreted to result from changing flow dynamics as flows travelled over the deformed sea floor, accentuating the structural topography by means of localised erosion and deposition. This study shows how differential subsidence acted as the ultimate control behind a range of processes leading to mounded stratigraphy. The models of the origin of the mounded morphologies are novel in the context of the North-Sea Palaeocene and have implications for the prediction of lithology in mounded basinal deposits, in the North Sea and elsewhere. 相似文献
27.
Beverly N. Goodman Eduard G. Reinhardt Hendrik W. Dey Joseph I. Boyce Henry P. Schwarcz Vasif Saholu Hayat Erkanal Michal Artzy 《地学学报》2009,21(2):97-104
Determining the position of Liman Tepe's (ancient `Clazomenae') archaeological features relative to the coastline is important for understanding their intended function and reconstructing the character of Aegean maritime activities and sea-based trade. Previous attempts at reconstructing harbour locations at Liman Tepe relied on extrapolating paleoenvironments based on modern surface topography. In light of this, samples from a sediment coring survey and terrestrial and underwater archaeological excavations were analysed using multi-proxy geoarchaeological methods to determine paleoenvironmental facies. Micropaleontological (foraminifera), sedimentological (grain-size analysis) and geochemical (δ13 C/δ18 O) analyses resulted in the reconstruction of the coastal paleogeomorphology, including the presence and absence of ancient harbouring areas. Neither of the previous coastal reconstructions was supported by the new results. Instead, two separate harbouring areas were recognized, one coincident with the Early Bronze Age (4800–3900 years bp) and a second during the archaic and classical periods ( c. 2800–2400 years bp). These results emphasize the necessity for multi-proxy geoarchaeological studies when approaching coastal archaeological sites as a means to reconstruct paleocoastal geomorphology and understand ancient maritime development better . 相似文献
28.
Eduard Bauerfeind Eva-Maria Nöthig Agnieszka Beszczynska Kirsten Fahl Lars Kaleschke Kathrin Kreker Michael Klages Thomas Soltwedel Christiane Lorenzen Jan Wegner 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1471-1487
Since 2000 long-term measurements of vertical particle flux have been performed with moored sediment traps at the long-term observatory HAUSGARTEN in the eastern Fram Strait (79°N/4°E). The study area, which is seasonally covered with ice, is located in the confluence zone of the northward flowing warm saline Atlantic water with cold, low salinity water masses of Arctic origin. Current projections suggest that this area is particularly vulnerable to global warming. Total matter fluxes and components thereof (carbonate, particulate organic carbon and nitrogen, biogenic silica, biomarkers) revealed a bimodal seasonal pattern showing elevated sedimentation rates during May/June and August/September. Annual total matter flux (dry weight, DW) at ~300 m depth varied between 13 and 32 g m?2 a?1 during 2000 and 2005. Of this total flux 6–13% was due to CaCO3, 4–21% to refractory particulate organic carbon (POC), and 3–8% to biogenic particulate silica (bPSi). The annual flux of all biogenic components together was almost constant during the period studied (8.5–8.8 g m?2 a?1), although this varied from 27% to 67% of the total annual flux. The fraction was lowest in a year characterized by the longest duration of ice coverage (91 and 70 days for the calendar year and summer season, May–September, respectively). Biomarker analyses revealed that organic matter originating from marine sources was present in excess of terrigenious material in the sedimented matter throughout most of the study period. Fluxes of recognizable phyto- and protozooplankton cells amounted up to 60×106 m?2 d?1. Diatoms and coccolithophorids were the most abundant organisms. Diatoms, mainly pennate species, dominated during the first years of the investigation. A shift in the composition occurred during the last year when numbers of diatoms declined considerably, leading to a dominance of coccolithoporids. This was also reflected in a decrease in the sedimentation of bPSi. The sedimentation of biogenic matter, however, did not differ from the amount observed during the previous years. Among the larger organisms, pteropods at times contributed significantly to both the total matter and CaCO3, fluxes. 相似文献
29.
Cumulative and differential cumulative seismic strain release of shallow earthquakes during 1964 through 1972 show significant time-delayed correlation for many of the rises and/or sinks of tectonic plate boundaries for the Atlantic, Indian and Pacific oceans. For the Pacific, time delays are almost exclusively from areas of higher to areas of lower strain release, and could imply viscous stress relaxation along or near the lithosphere—asthenosphere boundary. Seismically determined slip rates for many of the subduction zones during 1964–1972 are lower than those of the preceding part of the century by a factor of 5. The significant correlation between many rises and sinks suggests worldwide interaction and coupling of plate motion. 相似文献
30.