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261.
Vera Ponomareva Maxim Portnyagin Alexander Derkachev I. Florin Pendea Joanne Bourgeois Paula J. Reimer Dieter Garbe-Schönberg Stepan Krasheninnikov Dirk Nürnberg 《International Journal of Earth Sciences》2013,102(6):1673-1699
We report tephrochronological and geochemical data on early Holocene activity from Plosky volcanic massif in the Kliuchevskoi volcanic group, Kamchatka Peninsula. Explosive activity of this volcano lasted for ~1.5 kyr, produced a series of widely dispersed tephra layers, and was followed by profuse low-viscosity lava flows. This eruptive episode started a major reorganization of the volcanic structures in the western part of the Kliuchevskoi volcanic group. An explosive eruption from Plosky (M~6), previously unstudied, produced tephra (coded PL2) of a volume of 10–12 km3 (11–13 Gt), being one of the largest Holocene explosive eruptions in Kamchatka. Characteristic diagnostic features of the PL2 tephra are predominantly vitric sponge-shaped fragments with rare phenocrysts and microlites of plagioclase, olivine and pyroxenes, medium- to high-K basaltic andesitic bulk composition, high-K, high-Al and high-P trachyandesitic glass composition with SiO2 = 57.5–59.5 wt%, K2O = 2.3–2.7 wt%, Al2O3 = 15.8–16.5 wt%, and P2O5 = 0.5–0.7 wt%. Other diagnostic features include a typical subduction-related pattern of incompatible elements, high concentrations of all REE (>10× mantle values), moderate enrichment in LREE (La/Yb ~ 5.3), and non-fractionated mantle-like pattern of LILE. Geochemical fingerprinting of the PL2 tephra with the help of EMP and LA-ICP-MS analyses allowed us to map its occurrence in terrestrial sections across Kamchatka and to identify this layer in Bering Sea sediment cores at a distance of >600 km from the source. New high-precision 14C dates suggest that the PL2 eruption occurred ~10,200 cal BP, which makes it a valuable isochrone for early Holocene climate fluctuations and permits direct links between terrestrial and marine paleoenvironmental records. The terrestrial and marine 14C dates related to the PL2 tephra have allowed us to estimate an early Holocene reservoir age for the western Bering Sea at 1,410 ± 64 14C years. Another important tephra from the early Holocene eruptive episode of Plosky volcano, coded PL1, was dated at 11,650 cal BP. This marker is the oldest geochemically characterized and dated tephra marker layer in Kamchatka to date and is an important local marker for the Younger Dryas—early Holocene transition. One more tephra from Plosky, coded PL3, can be used as a marker northeast of the source at a distance of ~110 km. 相似文献
262.
263.
Tsunami hazard in coastal areas susceptible to flooding, although reduced (in terms of probability of occurrence), may pose a high risk. Therefore, in these areas, a detailed evacuation planning of the affected population is required as a risk mitigation measure. The knowledge and enforcement of evacuation routes may reduce the population vulnerability, making it more resilient and reducing risk. This paper presents a GIS approach for modelling evacuation routes based on the optimal path search problem, of the graph theory, which is implemented on ArcCasper tool. The methodology proposed considers the elements involved in the evacuation process, the worst credible tsunami inundation scenario (hazard extent and travel time), the number of people that needs to be evacuated in different time scenarios, the safe areas or destination points of the evacuation routes, the roads network characteristics and finally the time available to evacuate. The knowledge of those elements allows predicting some possible outcomes of the evacuation, such as the arrival time of the evacuees to a shelter and the identification of congestion hot spots resulting from the application of a flocking model which simulates the path to be used by evacuees avoiding obstacles. The municipality of Cascais was used to test the methodology proposed in this study. Cascais is one of the largest urban centres located about 25 km west of Lisbon, Portugal, with a high density of infrastructure along the coastline whereby most of the population and economic activities are exposed to a tsunami. The results, presented in the form of maps, allow identifying the optimal evacuation routes as well as the unfeasible routes. This crucial information could be used to the evacuation optimization regarding the location of meeting points and vertical shelters as well as to improve the accessibility of the areas to be evacuated. 相似文献
264.
Amanda Tosi Maria Elizabeth Zucolotto Diana Paula Andrade Othon Cabo Winter Daniela Cardozo Mourão Rafael Sfair Karen Ziegler Pablo Daniel Perez Sergio Suarez Iara Deniz Ornellas Marcelo Zurita Julio Cezar Mendes Alexander Wilhelm Kellner Wania Wolff 《Meteoritics & planetary science》2023,58(5):621-642
On August 19, 2020, at 13:18—UTC, a meteor event ended as a meteorite shower in Santa Filomena, a city in the Pernambuco State, northeast Brazil. The heliocentric orbital parameters resulting from images by cameras of the weather broadcasting system were semimajor axis a = 2.1 ± 0.1 au, eccentricity e = 0.55 ± 0.03, and inclination i = 0.15o ± 0.05. The data identified the body as an Apollo object, an Earth-crossing object with a pericenter interior to the Earth's orbit. The chemical, mineralogical, and petrological evaluations, as well as the physical analysis, followed several traditional techniques. The meteorite was identified as a H5-6 S4 W0 ordinary chondrite genomict breccia. The large amount of metal in the meteorite made a metallographic evaluation based on the opaque phases possible. The monocrystalline kamacite crystals suggest a higher petrological type and the distorted Neumann lines imply at least two different shock events. The absence of the plessite phase shows that the meteorite did not reach the highest shock levels S5 and S6. The well-defined polycrystalline taenite is indicative of petrologic types 4 and 5 due to the conserved internal tetrataenite rim at the boundaries. The presence of polycrystalline taenites and the characteristics of the Agrell Effect suggest that the Santa Filomena meteorite did not reheat above 700°C. The absence of martensite confirms reheating temperatures <800°C and a slow cooling rate. The Ni contents and sizes of the zoned taenite particles indicate a slow cooling rate ranging from 1 to 10 K Myr−1. 相似文献
265.
266.
Paula C.S. Carvalho Ana M.R. Neiva Maria M.V.G. Silva Eduardo A. Ferreira da Silva 《Chemie der Erde / Geochemistry》2014
Waters from abandoned Sb-Au mining areas have higher Sb (up to 2138 μg L−1), As (up to 1252 μg L−1) and lower Al, Zn, Li, Ni and Co concentrations than those of waters from the As-Au mining area of Banjas, which only contain up to 64 μg L−1 As. In general, Sb occurs mainly as SbO3− and As H2AsO4−. In general, waters from old Sb-Au mining areas are contaminated in Sb, As, Al, Fe, Cd, Mn, Ni and NO2−, whereas those from the abandoned As-Au mining area are contaminated in Al, Fe, Mn, Ni, Cd and rarely in NO2−. Waters from the latter area, immediately downstream of mine dumps are also contaminated in As. In stream sediments from Sb-Au and As-Au mining areas, Sb (up to 5488 mg kg−1) and As (up to 235 mg kg−1) show a similar behaviour and are mainly associated with the residual fraction. In most stream sediments, the As and Sb are not associated with the oxidizable fraction, while Fe is associated with organic matter, indicating that sulphides (mainly arsenopyrite and pyrite) and sulphosalts containing those metalloids and metal are weathered. Arsenic and Sb are mainly associated with clay minerals (chlorite and mica; vermiculite in stream sediments from old Sb-Au mining areas) and probably also with insoluble Sb phases of stream sediments. In the most contaminated stream sediments, metalloids are also associated with Fe phases (hematite and goethite, and also lepidocrocite in stream sediments from Banjas). Moreover, the most contaminated stream sediments correspond to the most contaminated waters, reflecting the limited capacity of stream sediments to retain metals and metalloids. 相似文献
267.
The Portuguese National Ecological Reserve (NER) was created in 1983, with the aim of preserving, in certain areas, the biophysical structure necessary to maintain exploitation of natural resources and land use without jeopardizing their sustainability. For the first time, issues related to groundwater resources were addressed. Since then, this legal tool has been revised for a better integration of the new national and European legislation and new scientific and technical knowledge. In the latest NER, the concept of “strategic areas of protection and aquifer recharge (SAPAR)” was created, being now necessary to define which are the methodologies and criteria to be applied for its delimitation. This paper summarizes the strategic guidelines that were established from debates held in several meetings with land-use planners, water resources managers, specialists and other stakeholders concerning the development of harmonized definitions and criteria of NER. As a result of those contributions a report was elaborated where guidelines and criteria for the NER delimitation were defined at national level, in accordance with national legislation and other relevant sector plans. In this work, the articulation and integration of SAPAR-protected areas in Portuguese Water Act and the expected difficulties of its application at operative level are evaluated since the SAPAR are important for the control of urban sprawl and therefore to preserve groundwater resources and dependent ecosystems. A brief explanation about the Portuguese main hydrogeological features is given for a better understanding of the groundwater resources and dependent ecosystems. Finally, the key guidelines for a good NER delimitation are compiled. 相似文献
268.
Dale Dominey-Howes Paula Dunbar Jesse Varner Maria Papathoma-Köhle 《Natural Hazards》2010,53(1):43-61
The Cascadia margin is capable of generating large magnitude seismic-tsunami. We use a 1:500 year tsunami hazard flood layer
produced during a probabilistic tsunami hazard assessment as the input to a pilot study of the vulnerability of residential and commercial buildings in Seaside, OR, USA. We map building
exposure, apply the Papathoma Tsunami Vulnerability Assessment Model to calculate building vulnerability and estimate probable maximum loss (PML) associated with a 1:500 year tsunami flood. Almost US$0.5 billion worth of buildings would be inundated, 95% of single
story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US$0.5 billion worth of buildings would be inundated, 95% of single
story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US116 million. These figures only
represent a tiny fraction of the total values of exposed assets and loss that would be associated with a Cascadia tsunami
impacting the NW Pacific coast. Not withstanding the various issues associated with our approach, this study represents the
first time that PML’s have ever been calculated for a Cascadia type tsunami, and these results have serious implications for
tsunami disaster risk management in the region. This method has the potential to be rolled out across the United States and
elsewhere for estimating building vulnerability and loss to tsunami. 相似文献
269.
We have developed a new approach to the problem of the chemical fingerprinting of artifacts manufactured from volcanic rocks of basaltic and andesitic composition. The method is an adaptation of standard energy-dispersive X-ray fluorescence spectrometry and is based on the observation that for irregularly-shaped rock fragments, the ratios of the intensities of the characteristic X-rays of certain trace elements are proportional to the ratios of the concentrations of those elements. This observation has allowed us to obtain geochemical data about the artifacts in a way that is rapid, inexpensive, and nondestructive, making it particularly suited to archaeological applications. We have used our approach to compare a suite of artifacts from an archaeological site in Martis Valley, near Truckee, California, with a group of lava flows from the surrounding area. Using a numerical measure of the geochemical difference between samples, we have been able to group the artifacts on the basis of their geochemistry, to determine which artifacts were manufactured from material found in Martis Valley and, in at least one case, to identify the lava flow that was the actual source of the lithic material for several of the artifacts. 相似文献