A survey instrument to isolate effectiveness of a novel risk communication intervention     

Anne M. Sanquini  Sundar M. Thapaliya  Michele M. Wood 《Natural Hazards》2016,82(1):59-72

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A rapid method for flood susceptibility mapping in two districts of Phatthalung Province (Thailand): present and projected conditions for 2050     

Michele Marconi  Beatrice Gatto  Michele Magni  Fausto Marincioni 《Natural Hazards》2016,80(1):329-350

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Has the Largest Field Been Discovered Yet? PETRIMES and GRASP 25 Years Later     

Gordon M. Kaufman  Ray Faith  John H. Schuenemeyer 《Mathematical Geosciences》2016,48(8):873-890

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Accurate ionospheric delay model for real-time GPS-based positioning of LEO satellites using horizontal VTEC gradient estimation     

Alfredo Renga  Flavia Causa  Urbano Tancredi  Michele Grassi 《GPS Solutions》2018,22(2):46

Ionospheric delays compensation is a mandatory step for precise absolute and relative positioning of Low Earth Orbit Satellites (LEO) by GPS measurements. The most frequently used ionosphere model for real-time GPS-based navigation in LEO is an isotropic model proposed by Lear, which uses the Vertical Total Electron Content (VTEC) above the receiver and a mapping function for TEC evaluation along a given ray path. Based on significant assessed results available for ground-based GPS receivers, we propose the use of a different model relying on the thin shell assumption and a bilinear horizontal variation of the VTEC as a function of latitude and longitude in the shell. It is expected that this model is capable of better describing horizontal gradients in the ionosphere, thus improving ionospheric delay estimation, especially in intense ionospheric conditions. This model is referred to as Linear Thin Shell (LTS). LTS performance in estimating undifferenced and double-differenced ionospheric delays is checked by comparing measured and predicted delays computed using flight data from the GRACE mission. Results show that the LTS always outperforms the isotropic model, especially in case of high solar activity. Moreover, the LTS model provides a higher performance uniformity over a wide range of ionospheric delays, thus ensuring good performance in different conditions. The results obtained demonstrate that the LTS model improves the ionosphere delays estimation accuracy by 20 and 40% for undifferenced and double-differenced delays, respectively. This suggests the LTS model can effectively contribute to improving precision in LEO positioning applications.  相似文献   

Temporal and bathymetric resolution of nautiloid death assemblages in stratigraphically condensed oozes (New Caledonia)          下载免费PDF全文

Adam Toma&#x;ových  Jn Schlgl  Darrell S. Kaufman  Natlia Hud kov 《地学学报》2016,28(4):271-278

Cephalopod shells can be affected by postmortem transport and biostratigraphic condensation, but direct estimates of the temporal and spatial resolutions of cephalopod assemblages are missing. Amino acid racemisation calibrated by ¹⁴C demonstrates a centennial‐scale time averaging (<500 years) of Nautilus macromphalus in sediment‐starved, epi‐ and mesobathyal pelagic environments. The few shells that are thousands of years old are highly degraded. The median occurrence of dead shells is at 445 m depth, close to the 300–400 m depth where living N. macromphalus are most abundant. Therefore, dead shells of this species accumulate at a centennial temporal resolution and with excellent bathymetric fidelity. Dead Nautilus shells exist for only a few hundred years on the seafloor, in contrast to the biostratigraphically condensed mixture of extant foraminifers and foraminifers that went extinct during the Pleistocene. Cephalopod shells that do not show any signs of early diagenetic cementation are unlikely to be biostratigraphically condensed.  相似文献   

Amphipod predation by the infaunal polychaete,Nephtys incisa     

Michele S. Redmond  K. John Scott 《Estuaries and Coasts》1989,12(3):205-207

Survival of the tubicolous amphipodAmpelisca abdita in a sediment toxicity test was negatively correlated with the presence of indigenousNephtys incisa. The gut contents ofN. incisa held in uncontaminated sediment included identifiable portions of the amphipods.A. abdita andMicrodeutopus gryllotalpa. Although most nephtyid polychaete worms are active predators,Nephtys incisa has been considered a nonselective deposit-feeder. We coclude thatN. incisa will prey upon amphipods under laboratory conditions. This predation may be a factor in the exclusion of surface-dwelling amphipods from theNephtys-Nucula community common in southern New England.  相似文献   

The effect of crystallization on the rheology and dynamics of lava flows     

Michele Dragoni  Andrea Tallarico 《Journal of Volcanology and Geothermal Research》1994,59(3)

The dynamics of a lava flow is studied by a two-dimensional model describing a viscous fluid with Bingham rheology, flowing down a slope. The temperature in the flow is calculated assuming that heat is transferred through the plug by conduction and is lost by radiation to the atmosphere at the top of the flow. Taken into account is that the increasing crystallization takes place in the flow as a consequence of cooling. The lava viscosity and yield stress are expressed as a function of crystallization degree as well as of temperature: in particular it is assumed that yield stress reaches a maximum value above the solidus temperature, according to experimental data. Dynamical variables, such as velocity and thickness of the flow, are calculated for different values of the maximum crystallization degree and the flow rate. The model shows how the lava flow dynamics is affected by cooling and crystallization. The cooling of the flow is controlled by the increase of yield stress, which produces a thicker plug and makes the heat loss slower. The increasing crystallization has two opposing effects on viscosity: it produces an increase of viscosity, but at the same time produces an increase of yield stress and hence reduces the heat loss and keeps the internal temperature high. As a consequence, lava flows are significantly affected by the dependence of yield stress on temperature and scarcely by the maximum crystallization degree.  相似文献   

What has seismic missed?     

Gordon Kaufman 《Natural Resources Research》1994,3(4):304-314

The relative efficiencies of alternative geometric patterns of both discrete borehole and continuous grid line search have been extensively discussed in the mathematical geology literature. However, an equally important problem has received virtually no attention: How to use a sample of properties of geologic anomalies detected by grid line search of a region to estimate systematically both the number and size distribution of geologic anomalies missed by the search. We show how estimation methods developed in the sample survey design literature can be adapted to this problem, and we apply these methods to data describing 94 anomalies identified by a seismic reconnaissance survey.  相似文献   

Reevaluation of the lake-sediment chronology in the Dead Sea basin, Israel, based on new Th/U dates     

Aaron Kaufman  Yoseph Yechieli  Michael Gardosh 《Quaternary Research》1992,38(3)

The Dead Sea is surrounded by chemical and detrital sediments that were deposited in its larger precursor lakes, Lake Samra and Lake Lisan. The sedimentary history of these lakes was recon-structed by means of ²³⁰Th/²³⁴U ages of 30 samples, mostly of argonite laminae, from 8 columnar sections up to 110 km apart. The general validity of the ages was demonstrated by subjecting them to tests of internal isotopic consistency, agreement with stratigraphic order, and concordance with ¹⁴C ages. In the south, only the part of the Samra Formation older than 170,000 yr is exposed, while the aragonite-detritus rhythmites found in the central and northern region are generally younger than 120,000 yr. The Lisan Formation started accumulating about 63,000 yr B.P., with the clay and aragonite beds in the south-central area reflecting a rise in water level to at least −280 m. The upper part of the Lisan Formation, the aragonite-rich White Cliff Member, started accumulating about 36,000 yr B.P. The lake probably reached its highest level sometime after this, based on the ages of Lisan sediments preserved in the southernmost reaches of the basin.  相似文献   

The historic and artistic heritage facing the earthquake risk: The Italian case     

Antonella Huber  Michele Dragoni 《Natural Hazards》1992,5(3):269-278

The problem of protection against earthquakes in Italy is made difficult by the presence of a huge historic and artistic heritage. Such a heritage is mainly made up of ancient buildings and monuments situated in the urban centres, which are densely distributed throughout Italy. Therefore, very complex problems are met in the determination of the value parameter concurring with the determination of seismic risk, in addition to hazard and vulnerability. An indication of the monetary value of a building is not sufficient as far as the cultural heritage is concerned: different criteria are necessary in order to distinguish which are the strategic buildings. If we consider that there are more than 2000 museums in Italy, most of which are placed inside historic buildings, it appears that museums should receive the highest priority in future initiatives for seismic rehabilitation.  相似文献