Tsunami hydrodynamic force on a building using a SPH real-scale numerical simulation     

Klapp  Jaime  Areu-Rangel  Omar S.  Cruchaga  Marcela  Aránguiz  Rafael  Bonasia  Rosanna  Godoy  Mauricio J.  Silva-Casarín  Rodolfo 《Natural Hazards》2020,100(1):89-109

Natural Hazards - One of the most important aspects in tsunami studies is the behaviour of the wave when it approaches the coast. Information on physical parameters that characterize waves is often...  相似文献   

Inter‐laboratory Characterisation of Apatite Reference Materials for Chlorine Isotope Analysis     

Alicja Wudarska  Ewa S&#x;aby  Michael Wiedenbeck  Jaime D. Barnes  Magali Bonifacie  Neil C. Sturchio  Grard Bardoux  Frdric Couffignal  Johannes Glodny  Linnea Heraty  Timm John  Christof Kusebauch  Sathish Mayanna  Franziska D. H. Wilke  Ewa Deput 《Geostandards and Geoanalytical Research》2021,45(1):121-142

Here we report on a set of six apatite reference materials (chlorapatites MGMH#133648, TUBAF#38 and fluorapatites MGMH#128441A, TUBAF#37, 40, 50) which we have characterised for their chlorine isotope ratios; these RMs span a range of Cl mass fractions within the apatite Ca₁₀(PO₄)₆(F,Cl,OH)₂ solid solution series. Numerous apatite specimens, obtained from mineralogical collections, were initially screened for ³⁷Cl/³⁵Cl homogeneity using SIMS followed by δ³⁷Cl characterisation by gas source mass spectrometry using both dual‐inlet and continuous‐flow modes. We also report major and key trace element compositions as determined by EPMA. The repeatability of our SIMS results was better than ± 0.10‰ (1s) for the five samples with > 0.5 % m/m Cl and ± 0.19‰ (1s) for the low Cl abundance material (0.27% m/m). We also observed a small, but significant crystal orientation effect of 0.38‰ between the mean ³⁷Cl/³⁵Cl ratios measured on three oriented apatite fragments. Furthermore, the results of GS‐IRMS analyses show small but systematic offset of δ³⁷Cl_SMOC values between the three laboratories. Nonetheless, all studied samples have comparable chlorine isotope compositions, with mean 10³δ³⁷Cl_SMOC values between +0.09 and +0.42 and in all cases with 1s ≤ ± 0.25.  相似文献   

Assessment of the development of aquifer management councils (COTAS) for sustainable groundwater management in Guanajuato, Mexico     

Philippus Wester  Ricardo Sandoval Minero  Jaime Hoogesteger 《Hydrogeology Journal》2011,19(4):889-899

Collective groundwater management by water users—self-regulation—is increasingly advocated as a complement to state regulation. This article analyzes the attempts by the Guanajuato State Water Commission (CEAG) in central Mexico to promote user self-regulation through the establishment and development of 14 Consejos Técnicos de Aguas (COTAS; Technical Water Councils). Based on a joint assessment by a former senior CEAG policy-maker and two researchers, Guanajuato’s groundwater-management policy is reviewed to understand why user self-regulation was less successful than expected. It concludes that increasing awareness and improving the knowledge base on groundwater is not enough to trigger self-regulation by groundwater users. A wider delegation of responsibilities to the COTAS is necessary, combined with: (1) functioning mechanisms for enforcing groundwater legislation, especially concerning well permits and pumped volumes, and (2) mechanisms that ensure the legitimacy and accountability of users??representatives to both users and state agencies.  相似文献   

The use of the exponent K(q) function to delimit homogeneous regions in regional frequency analysis of extreme annual daily rainfall          下载免费PDF全文

A. P. García‐Marín  J. Estévez  C. Sangüesa‐Pool  R. Pizarro‐Tapia  J. L. Ayuso‐Muñoz  F. J. Jimenez‐Hornero 《水文研究》2015,29(1):139-151

The regional frequency analysis of extreme annual rainfall data is a useful methodology in hydrology to obtain certain quantile values when no long data series are available. The most crucial step in the analysis is the grouping of sites into homogeneous regions. This work presents a new grouping criterion based on some multifractal properties of rainfall data. For this purpose, a regional frequency analysis of extreme annual rainfall data from the Maule Region (Chile) has been performed. Daily rainfall data series of 53 available stations have been studied, and their empirical moments scaling exponent functions K(q) have been obtained. Two characteristics parameters of the K(q) functions (γ_max and K(0)) have been used to group the stations into three homogeneous regions. Only five sites have not been possible to include into any homogenous regions, being the local frequency analysis of extreme daily rainfall the most appropriate method to be used at these locations. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Geophysical evidence for a large impact structure on the Falkland (Malvinas) Plateau          下载免费PDF全文

Maximiliano C.L. Rocca  Michael R. Rampino  Jaime L. Báez Presser 《地学学报》2017,29(4):233-237

A large, roughly circular structural basin is recognised on the Falkland (Malvinas) Plateau to the NW of West Falkland (Gran Malvina) Island (S 51°00′, W 62°00′). The basin, seen in seismic‐reflection profiles and evident as a large negative gravity anomaly, has a diameter of ~250 km. The age of the basin is estimated to be Late Palaeozoic. It is completely buried by younger sediments and has no topographic expression on the sea floor. We propose that the basin and geophysical anomalies, especially the combination of a large circular negative gravity anomaly with a rim of positive anomalies, and a marked circular series of positive magnetic anomalies in the same area, may be best explained by the presence of a large buried impact structure.  相似文献   

High-resolution seismic stratigraphy of the late Neogene of the central sector of the Colombian Pacific continental shelf: A seismic expression of an active continental margin     

Jaime Orlando Martínez  Eduardo López Ramos 《Journal of South American Earth Sciences》2011,31(1):28-44

The sedimentary prism of the central Pacific continental shelf of Colombia was affected by regional folding and faulting, and probably later mud diapirism, from the Late Miocene to the Holocene. Interpretation of high-resolution seismic lines (2 s/dt) revealed that the prism consists of 13 high-resolution seismic units, that can be separated into 5 seismic groups.Deposition of the prism and the associated stacking pattern, are probably the response to variable uplift and subsidence in a fore-arc basin that underwent important tectonic events by the end of the Miocene. Throughout the Pliocene, the continental shelf sedimentation was affected by the growing of a dome structure probable due to mud diapirism. This fact caused peripheral faults both normal and reverse that controlled the distribution of some of the seismic units. During the Late Pleistocene (Wisconsin stage?) a eustatic sea level fall caused the shoreline to advance about 50 km westward of its present position. Because of this eustatic sea level change, a strong fluvial dissection took place and is interpreted as the probable extension of the San Juan River to the south of the present day river mouth. Within this framework it is believed that the Malaga and Buenaventura Bays were the passageways of branches of the old drainage system of the San Juan River. The inner branch circulated through the present Buenaventura Bay and runs southward leaving the mark of an apparent valley identified in the seismic information in the eastern sector of the study area. This old fluvial valley and its filling material located in the present day inner continental shelf front of Buenaventura are postulated as important targets to find placer minerals such as gold and platinum.  相似文献   

Patterns of biomass-size spectra from oligotrophic waters of the Northwest Atlantic     

Renato A. Quinones  Trevor Platt  Jaime Rodríguez 《Progress in Oceanography》2003,57(3-4):405

The study of the distribution of biomass by size provides an ataxonomic approach for analyzing the structure of the pelagic ecosystem. However, empirical data regarding planktonic size-structure in offshore areas are scarce. Here, we report the results of a study of the planktonic biomass size-distribution at several stations located within two regions (Sargasso Sea and New England Seamounts Area) of the Northwest Atlantic. The biomass size-spectra covered a body-size range from bacteria to mesozooplankton and a depth range from the surface to 400 m. It is shown that the slope of the normalized biomass size-spectrum (NBS-spectrum) varies depending on whether volume or carbon units are used. The transformation from volume to carbon units makes the slope of the NBS-spectrum approximately 0.15 units more negative. The distribution of normalized-biomass by size was linear (plotted on a log–log scale) at all stations. The slopes of the NBS-spectra (volume scale) ranged from −0.96 to −1.01. There were no significant differences among the slopes of the NBS-spectra within either of the two areas studied. In addition, no significant differences were detected between the stations in the Sargasso Sea and those located in the New England Seamounts area. Apart from a tendency towards a decrease in the intercept of the normalized-biomass axis of the size-spectra in deeper waters, the NBS-spectra were also very similar through depth. The slopes of the NBS-spectra in biovolume units are not significantly different from −1.0 (p<0.01), and therefore are in agreement with Sheldon’s Linear Biomass Hypothesis. By contrast, the slopes of the NBS-spectra in carbon units are significantly different (p<0.01) from −1.0 (range=–1.09 to –1.17; all stations TOGETHER=–1.14) and their numerical values are in close agreement with Platt and Denman’s model and with the findings of [Rodríguez and Mullin, 1986a]) for the North Pacific Central Gyre. The results of this study support the hypothesis that the planktonic size-structure of offshore oligotrophic systems is a conservative property.  相似文献   

Zooplankton and the oceanography of the eastern tropical Pacific: A review   总被引：2，自引：5，他引：2  

María Ana Fernndez-lamo  Jaime Frber-Lorda 《Progress in Oceanography》2006,69(2-4):318

We review the spatial and temporal patterns of zooplankton in the eastern tropical Pacific Ocean and relationships with oceanographic factors that affect zooplankton distribution, abundance and trophic relationships. Large-scale spatial patterns of some zooplankton groups show broad coincidence with surface water masses, circulation, and upwelling regions, in agreement with an ecological and dynamic partitioning of the pelagic ecosystem. The papers reviewed and a new compilation of zooplankton volume data at large-scale show that abundance patterns of zooplankton biomass have their highest values in the upwelling regions, including the Gulf of Tehuantepec, the Costa Rica Dome, the equatorial cold tongue, and the coast of Peru.Some of the first studies of zooplankton vertical distribution were done in this region, and a general review of the topic is presented. The possible physiological implications of vertical migration in zooplankton and the main hypotheses are described, with remarks on the importance of the oxygen minimum zone (OMZ) as a barrier to both the vertical distribution and migration of zooplankton in the region. Recent results, using multiple-net gear, show that vertical distribution is more complex than previously thought. There are some well-adapted species that do live and migrate within the OMZ.Temporal patterns are reviewed and summarized with historical data. Seasonal variations in zooplankton biomass follow productivity cycles in upwelling areas. No zooplankton time series exist to resolve ENSO effects in oceanic regions, but some El Niño events have had effects in the Peru Current ecosystem. Multidecadal periods of up to 50 years show a shift from a warm sardine regime with a low zooplankton biomass to a cool anchovy regime in the eastern Pacific with higher zooplankton biomasses. However, zooplankton volume off Peru has remained at low values since the 1972 El Niño, a trend opposite to that of anchoveta biomass since 1984.Studies of trophic relations emphasize the difference in the productivity cycle in the eastern tropical Pacific compared to temperate or polar ecosystems, with no particular peaks in the stocks of either zooplankton or phytoplankton. Productivity is more dependent on local events like coastal upwelling or water circulation, especially in the equatorial countercurrent and around the equatorial cool-tongue. Micrograzers are very important in the tropics as are predatory mesozooplankton. Up to 70% of the daily primary productivity is consumed by microzooplankton, which thus regulates the phytoplankton stocks. Micrograzers are an important link between primary producers, including bacteria, and mesozooplankton, constituting up to 80% of mesozooplankton food. Oceanography affects zooplankton trophic relationships through spatial–temporal effects on primary productivity and on the distributions of metabolic factors, food organisms, and predators. This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific.  相似文献   

Coupled climate impacts of the Drake Passage and the Panama Seaway     

Simon Yang  Eric Galbraith  Jaime Palter 《Climate Dynamics》2014,43(1-2):37-52

Tectonically-active gateways between ocean basins have modified ocean circulation over Earth history. Today, the Atlantic and Pacific are directly connected via the Drake Passage, which forms a barrier to the time-mean geostrophic transport between the subtropics and Antarctica. In contrast, during the warm early Cenozoic era, when Antarctica was ice-free, the Drake Passage was closed. Instead, at that time, the separation of North and South America provided a tropical seaway between the Atlantic and Pacific that remained open until the Isthmus of Panama formed in the relatively recent geological past. Ocean circulation models have previously been used to explore the individual impacts of the Drake Passage and the Panama Seaway, but rarely have the two gateways been considered together, and most explorations have used very simple atmospheric models. Here we use a coupled ocean–ice–atmosphere model (GFDL’s CM2Mc), to simulate the impacts of a closed Drake Passage both with and without a Panama Seaway. We find that the climate response to a closed Drake Passage is relatively small when the Panama Seaway is absent, similar to prior studies, although the coupling to a dynamical atmosphere does increase the temperature change. However, with a Panama Seaway, closing Drake Passage has a much larger effect, due to the cessation of deep water formation in the northern hemisphere. Both gateways alter the transport of salt by ocean circulation, with the Panama Seaway allowing fresh Pacific water to be imported to the North Atlantic, and the Drake Passage preventing the flow of saline subtropical water to the circum-Antarctic, a flow that is particularly strong when the Panama Seaway is open. Thus, with a Panama Seaway and a closed Drake Passage, the Southern Ocean tends to be relatively salty, while the North Atlantic tends to be relatively fresh, such that the deep ocean is ventilated from the circum-Antarctic. Ensuing changes in the ocean heat transport drive a bi-polar shift of surface ocean temperatures, and the Intertropical Convergence Zone migrates toward the warmer southern hemisphere. The response of clouds to changes in surface ocean temperatures amplifies the climate response, resulting in temperature changes of up to 9 °C over Antarctica, even in the absence of land-ice feedbacks. These results emphasize the importance of tectonic gateways to the climate history of the Cenozoic, and support a role for ocean circulation changes in the glaciation of Antarctica.  相似文献   

Mercury colonial footprint in Darién Gulf sediments,Colombia     

Alex Rúa  Gerd Liebezeit  Jaime Palacio-Baena 《Environmental Earth Sciences》2014,71(4):1781-1789

The mercury (Hg) deposition history in the Darién Gulf is reconstructed from three sediment cores spanning up to 1,000 years. Knowledge on the contribution to global Hg budget from the Caribbean is limited. Patterns of water circulation, sediment deposition rates, cataclysmic atmospheric inputs, and post-depositional migration have been considered in Hg trapping in the seabed. The sediment delivery rates to the coastal zone over the Late Holocene have increased from 0.2 to 1 cm year^?1 owing to anthropogenic influence. This alteration took the form of geological effects, like coastal morphology change, that played a major role in Hg downcore signal preservation. Natural background Hg levels in Southern Caribbean sediments (77.0 μg kg^?1) are up to three times higher than preindustrial signals at other latitudes, because of volcanic contributions from the Pacific ring of fire. Enrichment factors rose from 0.9 to 1.5 (70.1–113.5 μg kg^?1) within profiles related to Hg usage since Spanish colonial times between the calendar years 1550 and 1811.  相似文献