Dimensional analysis of yielding and pounding structures for records without distinct pulses

The seismic response of two fundamental mechanical configurations of earthquake engineering, the elastic–plastic system and the pounding oscillator, is revisited with the aid of dimensional analysis. Starting from the previous work of the authors which focused on pulse-type excitations, the paper offers an alternative, yet physically motivated, way to present the response of yielding and pounding structures under excitations with arbitrary time history. It is shown, that when the appropriate time and length scales are adopted, dimensional analysis can be implemented and remarkable order emerges in the response. Regardless of the acceleration level and frequency content of the excitation, all response spectra become self-similar and when expressed in dimensionless terms, resulting from dimensional analysis, follow a single master curve. The study proposes such scales together with the associated selection criteria among the available in literature strong ground motion parameters and shows that the proposed approach reduces drastically the scatter in the response.     

Multi-isotope (Ba,C, O) partitioning during experimental carbonatization of a hyper-alkaline solution

Carbonates formed from hyperalkaline aqueous solutions at the Earth?s surface are known to bear the most extreme disequilibrium isotope signatures reported so far in nature. We present here the results for stable carbon (C), oxygen (O), and barium (Ba) isotope fractionation during the precipitation of witherite (BaCO₃) induced by the chemical absorption of atmospheric carbon dioxide (CO₂) into an aqueous hyper-alkaline solution (at 4° and 21?°C; 1?atm total pressure). Independent from temperature, the barium carbonate formation was associated with a substantial enrichment of the lighter C and O isotopes in the solid compared to the atmosphere (C, O), close to previous results found in experiments and nature. A new approach is introduced to explain oxygen isotope fractionation upon hydroxylation of CO₂. With Ba isotope enrichment factors between ?0.45 and ?0.53‰ (^138/134ε) or ?0.34 and ?0.40‰ (^137/134ε), respectively, the synthesized BaCO₃ displays the highest kinetic enrichment of the light Ba isotope in the carbonate solid reported so far.     

A comparison of rainfall estimation techniques for sub-Saharan Africa

Interpolated rain-gauge data were compared to Meteosat-based precipitation estimates for sub-Saharan Africa. Validation was carried out using a dataset from a very dense gauge network in South Africa, on a point-to-pixel (PO–PI) as well as on a pixel-to-pixel (PI–PI) basis. Error criteria computed at the gauged pixels indicate that overall the interpolated estimates perform similarly to the satellite-based data: they provide good estimates of lower but underestimate larger precipitation amounts. It is concluded that the satellite estimates are more fitted for the operational modelling of processes such as surface runoff and soil erosion, especially in the developing areas where resources are scarce.     

Trends in extreme rainfall in the state of New South Wales,Australia

The trends in annual maximum rainfall (AMR) intensity data in New South Wales, Australia, were examined. Data from 60 stations were used covering three study periods, 1955–2010, 1965–2010 and 1978–2010. Mann-Kendall (MK) and Spearman’s rho (SR) tests were applied to assess trends at local stations. Pre-whitening (PW), trend-free pre-whitening (TFPW) and the variance correction (VC) tests were used to assess the effects of serial correlation on trend results. For regional trend analysis, the regional MK test was employed. The impacts of climatic variability modes on the observed trends in AMR intensity and seasonal maximum rainfall data were investigated. It was found that positive trends were more frequent than the negative ones. The PW, TFPW and VC tests resulted in a slight reduction in the count of stations exhibiting significant positive trends. The number of stations exhibiting significant trends decreased when the impact of climate variability modes was considered.     

Implications for eruptive processes as indicated by sulfur dioxide emissions from K lauea Volcano, Hawai‘i, 1979–1997

K lauea Volcano, Hawai‘i, currently hosts the longest running SO₂ emission-rate data set on the planet, starting with initial surveys done in 1975 by Stoiber and his colleagues. The 17.5-year record of summit emissions, starting in 1979, shows the effects of summit and east rift eruptive processes, which define seven distinctly different periods of SO₂ release. Summit emissions jumped nearly 40% with the onset (3 January 1983) of the Pu‘u ‘ ‘ -K paianaha eruption on the east rift zone (ERZ). Summit SO₂ emissions from K lauea showed a strong positive correlation with short-period, shallow, caldera events, rather than with long-period seismicity as in more silicious systems. This correlation suggests a maturation process in the summit magma-transport system from 1986 through 1993. During a steady-state throughput-equilibrium interval of the summit magma reservoir, integration of summit-caldera and ERZ SO₂ emissions reveals an undegassed volume rate of effusion of 2.1×10⁵ m³/d. This value corroborates the volume-rate determined by geophysical methods, demonstrating that, for K lauea, SO₂ emission rates can be used to monitor effusion rate, supporting and supplementing other, more established geophysical methods. For the 17.5 years of continuous emission rate records at K lauea, the volcano has released 9.7×10⁶ t (metric tonnes) of SO₂, 1.7×10⁶ t from the summit and 8.0×10⁶ t from the east rift zone. On an annual basis, the average SO₂ release from K lauea is 4.6×10⁵ t/y, compared to the global annual volcanic emission rate of 1.2×10⁷ t/y.     

Climate change and agricultural pollution effects on the trophic status of a Mediterranean lake

Trichonis Lake is the largest natural freshwater body in Greece with a surface area of 97 km². It receives pollutants from numerous anthropogenic activities, especially from intensive agricultural practices, urban sewages, stock grazing land and small industries. In this study, hydrologic and chemical parameters are assessed during two periods (1990–1991) and (2001–2002) to evaluate the effects of the climatic changes on phosphorous trends and consequently on the trophic status of Trichonis Lake. Even though large quantities of fertilizers are applied in the lake's catchment, phosphorus loads are still in the permissible level as estimated according to Vollenweider's relationship based on total phosphorus concentration. Due to relatively higher rainfall precipitation during the last years, an increased amount of the phosphorus entering into the lake system is flushed out, thus keeping the trophic status of the lake in oligotrophic levels. In contrast, lower rainfall rates during the first period (1990–1991) have led to the decrease in phosphorus flush out and its detainment into the lake water and sediment resulting to mesotrophic conditions. As the trophic status of the lake is mainly hydrologically dependent and thus unpredictable, effective management plans targeting the elimination of nutrient pollution loadings are necessary.     

Provenance and tectonic setting of the metapelites deposits in the Bulfat Complex,NE-Iraq

Major and trace elements including rare earth elements (REEs) chemistry of the metapelitic rocks of Bulfat Complex (Iraqi Zagros Suture Zone) indicate their enrichment in large-ion Lithophile, light rare earth (LREE) elements, and relative depletion of high field strength and heavy rare earth (HREE) elements. The linear correlation coefficients between TiO₂, K₂O, and Al₂O₃ and total REE reveal that phyllosilicates (e.g., mica) and accessory minerals mainly Ti-bearing phases (e.g., ilmenite) are likely the dominant hosts for REEs. Chondrite-normalized REE patterns typical of continental margin settings with significant enrichment of LREE, prominent negative Eu anomalies, and nearly flat HREE are positively correlated with post-Archean Australian shale (PAAS) and upper continental crust (UCC) patterns. Additionally, their consistent elemental La/Sc, Th/Sc, La/Co, Th/Co, Cr/Th, and Eu/Eu* values suggest that sediments may have been originally derived from an old post-Archean upper continental crust composed chiefly of granitic component. It seems most likely that the felsic source rocks were originated by a process of intra-crustal differentiation such as partial melting and/or fractional crystallization involving fractionation of Ca-plagioclase. The geochemical evidences particularly REEs evaluation show that deposition of clasts occurred in an active continental margin setting during lower–upper Cretaceous period contemporaneous with the igneous activities. It is evident therefore that the clasts source is from the north–northeast side, i.e., from the active margin of Iranian microcontinent (Sanandaj–Sirjan Zone).     

The environment of Upper Palaeolithic (Magdalenian and Azilian) hunters at Hauterive‐Champréveyres,Neuchâtel,Switzerland, interpreted from coleopteran remains

An excavation primarily intended to investigate the Bronze Age deposits at Hautrive‐Champréveyres, Neuchâtel, Switzerland, encountered beneath the Bronze Age levels a sequence of Late‐glacial sediments that were deposited between about 13000 yr BP and 11800 yr BP. Within these deposits Upper Palaeolithic hearths, bones and flint implements were found in a context that left no doubt that they accumulated on the actual living floors. Two separate cultures were involved; an earlier Magdalenian one overlain by a rather later Azilian assemblage. Coleoptera from the associated organic silts and sands provide detailed ecological and climatic information about the time when these people lived in the area. Radiocarbon dates indicate that the Magdalenians lived in the area at about 13000 yr BP. The Coleoptera show that the mean July temperature at this time was about 9°C and mean temperature of the coldest month was about −25°C. The landscape was bare of trees with an open patchy vegetation. Shortly after the area was abandoned by the Magdalenian hunters, the climate became suddenly warmer and mean July temperatures rose abruptly to at least 16°C and winter temperatures rose to levels not much different from those of the present day. There is evidence that at this time, intense slope instability and mud flows may have rendered the locality unsuitable for human occupation. About seven centuries after the episode of sudden climatic warming, namely at about 12300 yr BP, palaeolithic Azilian hunters occupied the area at a time when the climate was thoroughly temperate and the landscape was clothed in birch and willow woodland. This was gradually replaced by pine forest at the top of the sequence and Late‐glacial deposition ceased by about 11800 yr BP. Copyright © 2000 John Wiley & Sons, Ltd.     

A New Species of Amsassia from the Ordovician of Korea and South China: Paleobiological and Paleogeographical Significance

A new species of the probable calcareous alga Amsassia, A. koreanensis, is recognized from the Duwibong Formation (Middle Ordovician, Darriwilian) of the Taebaeksan Basin in mid-eastern Korea. This is the first report of the genus from the Korean Peninsula, expanding its geographical range to the eastern Sino-Korean Block. The new species also occurs in the Xiazhen Formation (Upper Ordovician, Katian) at Zhuzhai in the South China Block. Amsassia koreanensis is the smallest species of this modular genus, having a maximum module diameter of 0.28 mm. Module increase is by bipartite, tripartite and quadripartite types of longitudinal axial fission, but unlike other species of the genus, quadripartite fission is common. The types of fission are comparable to those in some Tetradiida (now Prismostylales, florideophycean rhodophyte algae), although the processes of fission are different. The distribution of A. koreanensis further strengthens the biogeographical connection between the Sino-Korean and South China blocks, suggesting that these two paleocontinents were located closer together during the Middle to Late Ordovician than previously speculated.