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111.
112.
J. Zlotnicki Y. Sasai J. P. Toutain E. U. Villacorte A. Bernard Julio P. Sabit Juan M. Gordon Jr Ernesto G. Corpuz M. Harada J. T. Punongbayan H. Hase T. Nagao 《Bulletin of Volcanology》2009,71(1):29-47
Since 1572, 33 phreatic to phreatomagmatic eruptions have occurred on Taal volcano (Philippines), some of them causing several
hundred casualties. Considering the time delay between two consecutive eruptions, there is an 88% probability that Taal volcano
should have already erupted. Since 1992, several phases of seismic activity have been recorded accompanied by ground deformation,
opening of fissures, and surface activity. The volcanic activity of Taal appears to be controlled by dike injections and magma
supply, buffered by a hydrothermal system that releases fluids and heat through boiling and subsequent steaming. In early
2005, a multidisciplinary project was launched for studying the hydrothermal activity. To map the hydrothermal system, combined
surveys were carried out to investigate self-potential, total magnetic field, ground temperature and carbon dioxide soil degassing,
along with satellite thermal imaging of the Main Crater Lake. The elevated temperatures and high concentrations of carbon
dioxide, as well as electromagnetic anomalies, indicate large-scale hydrothermal degassing. This process is enhanced along
the tectonic features (e.g., crater rim and faults) of the volcano, while active fissures opened along the E–W northern flank
during the 1992–1994 seismic activity. Heat and fluids from the hydrothermal system are essentially released in the northern
part of the crater, which is bounded to the South by a suspected NW–SE fault along which seismicity seems to take place, and
dikes are thought to be intruded. During the January 2005 surveys, a new seismic crisis started, and the felt earthquakes
prompted spontaneous evacuation of hundreds of inhabitants living on the volcano. Repeated surveys show changes of self-potential,
total magnetic field, and ground temperature with time, without any noticeable spatial enlargement. These observations suggest
that the northern flank located between the crater rim and the 1992–1994 fissures is connected with a deep thermal source
in Main crater and is reactivated during seismic crises. This sector could be subjected to flank failure. 相似文献
113.
Paola de Ruggiero Ernesto Napolitano Roberto Iacono Stefano Pierini Giancarlo Spezie 《Ocean Dynamics》2018,68(12):1683-1694
In this study, a baroclinic coastal trapped wave, with period ~?4.5 days and cross-shore scale ~?3 km, is identified in the outputs of a very-high-resolution ocean circulation model of the Campania coastal system (central Tyrrhenian Sea; including the Gulfs of Salerno, Naples, and Gaeta). The outputs are from a simulation spanning June 2003, a month in which the surface winds were always weak, except for a strong northeasterly wind event that lasted 1 day (20 June). This event is found to generate a strong upwelling along the Campania coasts, whose relaxation—virtually free, because of the weakness of the winds—produces coastal current fluctuations that propagate to the north, spanning the three gulfs. The dynamics (analyzed with a focus on the Gulf of Naples) is found to share important features with baroclinic Kelvin waves in a two-layer model, such as the sharp cross-shore decrease of the perturbation amplitude and the vertical reversal of the long-shore current velocities. The simulated phase speed, cross-shore extension, and wavelength of the perturbation are also close to those obtained using a two-layer approximation of the dynamics. Moreover, the propagation described by the models is shown to be compatible with current measurements that were made in June 2003 at the southern entrance of the Gulf of Naples. Experimental implications related to the specific oceanographic problem are finally discussed, and an experimental strategy—inspired by our modeling approach—aimed at identifying the phenomenon is proposed. 相似文献
114.
115.
In this paper we present an extension of the ensemble Kalman filter (EnKF) specifically designed for multimodal systems. EnKF
data assimilation scheme is less accurate when it is used to approximate systems with multimodal distribution such as reservoir
facies models. The algorithm is based on the assumption that both prior and posterior distribution can be approximated by
Gaussian mixture and it is validated by the introduction of the concept of finite ensemble representation. The effectiveness
of the approach is shown with two applications. The first example is based on Lorenz model. In the second example, the proposed
methodology combined with a localization technique is used to update a 2D reservoir facies models. Both applications give
evidence of an improved performance of the proposed method respect to the EnKF. 相似文献
116.
Gabriela Ferracutti Ernesto Bjerg Aberra Mogessie 《International Journal of Earth Sciences》2013,102(3):701-720
The layered mafic–ultramafic rocks in the Sierras de San Luis, Argentina (Las Águilas, Las Higueras and Virorco), constitute a 3–5-km-wide belt that extends over 100 km from NE to SW. They carry a sulphide mineralization consisting of pyrrhotite, pentlandite and chalcopyrite, in veins and as disseminated to massive ore. Disseminated spinels are frequently associated with the sulphide minerals as well as platinum group minerals. A strong correlation between S, Ni, Co, Cu, Cr, Pt and Pd indicates the presence of one to three levels of mineralization within the ultramafic units. The maximum concentration of these elements coincides with the units containing platinum group minerals (PGM) and spinel group minerals. This clear relationship constitutes a good prospecting guide in the search for layers with high-grade ore, probably associated with deeper stratigraphic levels where ultramafic rocks are dominant. The bulk rock chemistry and concentrations of metals and platinum group elements as well as textural evidence suggest that the parental magma was mafic with tholeiitic affinities and MgO rich. The Las Águilas layered mafic–ultramafic body and the remaining bodies in the area bear similar characteristics to well-known stratified complexes developed in extensional tectonic regimes, as it is the case of Jinchuan (China), Kabanga (Tanzania) and Fiambala (Argentina). 相似文献
117.
V. Ernesto Méndez Christopher M. Bacon Meryl Olson Katlyn S. Morris Annie Shattuck 《The Professional geographer》2013,65(3):357-376
We used households as the primary unit of analysis to synthesize agrobiodiversity research in small-scale coffee farms and cooperatives of Nicaragua and El Salvador. Surveys, focus groups, and plant inventories were used to analyze agrobiodiversity and its contribution to livelihoods. Households managed high levels of agrobiodiversity, including 100 shade tree and epiphyte species, food crops, and medicinals. Small farms contained higher levels of agrobiodiversity than larger, collectively managed cooperatives. Households benefited from agrobiodiversity through consumption and sales. To better support agrobiodiversity conservation, our analysis calls for a hybrid approach integrating bottom-up initiatives with the resources from top-down projects. 相似文献
118.
119.
Summary. Palaeomagnetic results for a sequence of Permocarboniferous rhythmites presented in the previous paper have been submitted to maximum entropy spectral analysis to test whether these palaeomagnetic data could supply information on geomagnetic variations. There is a good correlation between the thickness of the rhythmites and sunspot spectra, suggesting that these sediments are really seasonal. The palaeomagnetic spectra are compared with those of observatory records. Periods of approximately 24.4, 12.4, 8.6, 6.7 and 5.5 found for palaeomagnetic data have corresponding values in the geomagnetic spectrum. Most of these periods, however, are the same as those found in the thickness data, implying that magnetization can be influenced by the sedimentation process as suggested by other investigators. On the other hand, both geomagnetic and climatic (thickness) variations seem to be related to solar activity. Therefore, at least indirectly, palaeomagnetic data may reflect geomagnetic variations. 相似文献
120.
Chlorine atom-initiated photooxidations of CH2FCF3 (HFC-134a) in O2-N2 diluent were carried out to identify the products formed from the \(CF_3 CHF\dot O\) radical reactions and to determine the product yields as a function of temperature, pressure and O2 concentration. CF3C(O)F and HC(O)F were the major ‘first-generation’ products observed, along with smaller yields of C(O)F2 and, as yet, undetermined yields of CF3OOOCF3 and CF3OOC(O)F. The relative importance of the two major \(CF_3 CHF\dot O\) reaction pathways, is expressed by the rate constant ratio $$k_{O_2 } /k_d = 3.2 \times 10^{ - 25} e^{(3510 \pm 470)/T} cm^3 molecule^{ - 1}$$ The decomposition reaction leading to HC(O)F and ?F3 radical products is predicted to be the dominant pathway at the Earth's surface while mainly CF3C(O)F formation will occur at the tropopause. 相似文献