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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
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The use of archaeology to study earthquake hazards provides a human dimension to an issue of modern societal concern. We developed an archaeoseismic approach to the study of prehistoric earthquakes on active strike-slip faults. This approach employs a combination of standard archaeological and paleoseismic techniques. We have successfully applied this approach and its attendant methods to an archaeological site that straddles and has been offset by the San Andreas fault in northern coastal California. Resultant fault parameters, including cumulative rate of slip and timing of the penultimate event, are comparable to results of strictly paleoseismic investigations at other sites on this fault. The archaeoseismic approach furnishes a number of advantages over geologic studies in terms of the availability and number of potential study sites, the abundance of datable materials, and the array of potential piercing features with which to constrain fault history. © 1997 John Wiley & Sons, Inc. 相似文献
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Barry N. Noller Roger A. Watters Peter H. Woods 《Journal of Geochemical Exploration》1997,58(1):37-50
The Ranger Uranium Mine located in the Alligator Rivers Region of the Northern Territory lies in the tropical zone and has an annual wet-dry monsoonal climate. Following the commencement of the wet season, runoff from the waste rock dump accumulates in a retention pond (RP4). This water is permitted to discharge to the nearby Magela Creek once minimum flow of 5 m3/sec is reached and following filling of the pond. The discharge proceeds via a channel, experimental wetland and a backflow billabong (Djalkmarra Billabong) which acts as a natural wetland filter and flows out to Magela Creek.This study examines monitoring data for water releases over 3 wet seasons. I wet season with no release and 4 dry seasons. The monitoring data comprised electrical conductivity (EC). pH, Na, K. Ca, Mg. HCO−3 SO2−4, Cl− and U (total or filtered, < 0.45 μm). Some ICP-MS scans of trace elements were also undertaken with particular reference being made to Re and U.Specific features of the sequence of water accumulation, release and reconstitution of Djalkmarra Billabong are able to show that U is effectively removed from solution, from about 50 ppb down to < 1 ppb. Soluble salts may remain in the water column and are removed by dilution following discharge to Magela Creek. Sediment levels show no increase in U concentration with time.The pH of the billabong water during releases (6.0–6.6) suggests that cationic forms of U, such as (UO2)3 (OH)5, predominate, favouring adsorption on to the humic-rich sediments of the natural wetland. The application of this principle enables U to be removed efficiently from waste water and to be contained within the mine lease. 相似文献
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Allometric relationships and peak-season community biomass stocks of native shrubs in Senegal's Peanut Basin 总被引：1，自引：0，他引：1
A. Lufafa I. Diédhiou N.A.S. Ndiaye M. Séné F. Kizito R.P. Dick J.S. Noller 《Journal of Arid Environments》2009,73(3):260-266
Allometric equations and community biomass stocks are presented for Guiera senegalensis J.F. Gmel (Gs) and Piliostigma reticulatum (DC.) Hochst (Pr) – two native shrub species in the Sahel. These shrubs are of interest because they dominate semi-arid sub-Sahalien Africa but have been largely overlooked as a key biomass component and regulator of ecosystem composition and function in this landscape. In Year 1, best predictors of aboveground biomass were height and number of stems (Gs) and crown diameter (Pr); and for belowground biomass were height and basal diameter (Gs) and basal diameter (Pr). In Year 2, height and crown diameter were the best predictors of aboveground biomass (R2 = 0.90 for Gs and 0.87 for Pr), whereas basal diameter and number of stems (Gs) and basal diameter (Pr) were best predictors of belowground biomass. Peak-season biomass estimates ranged from 0.44 to 4.58 ton ha?1 (mean = 2.38 ton ha?1) in the Gs sites and from 0.33 to 7.38 ton ha?1 (mean = 3.71 ton ha?1) in the Pr communities. Both species exhibited unusually large root:shoot ratios (4.5:1 for Gs and 10.2:1 for Pr). Although models differ between years, allometric relationships provide reasonable biomass estimates for Gs and Pr. 相似文献
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