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21.
Some earthquakes in the Eastern Mediterranean are tsunamigenic and some of their tsunamis affected the coastal area of the
Gulf of Fethiye, SW Turkey. Recent trenching surveys on the low-lying coastal areas of Dalaman delta beach across the Rhodes
Pass revealed three probable tsunami impacts as a result of the historical earthquakes of 1303, 1481 and 1741. Yet, there
have been relatively few studies of the processes associated with tsunami sediment transport, their deposition and nature
in geological record. In addition to the interpretation of sedimentary features, accurate paleoenvironmental assessments might
be possible by distinctive biogeochemical researches on marine-sourced organic matters, geochemical properties, quantitative
amounts of marine-sourced biomarkers and deterministic ratios. The identification of major lipid biomarkers (fatty acids and
sterols) in the samples recovered from the sidewalls of the studied trench, for example, indicated biogenic contributions
due to the presence of phytoplankton, zooplankton, dinoflagellates and bacteria. Quantitative estimation of biomarkers and
deterministic ratios also indicated some evidences for marine-sourced organic matters, implying that biomarkers can be used
to answer the open questions in tsunami and paleotsunami researches. 相似文献
22.
The earthquakes and related tsunamis of October 6, 1944 and March 7, 1867; NE Aegean Sea 总被引：1，自引：0，他引：1
During two distinct earthquakes occurred on March 7, 1867 and October 6, 1944, tsunami waves were also observed at some localities
around the Gulf of Edremit, NE Aegean Sea. The first event (M
w = 6.8) mostly affected the city of Mitilini of Lesvos Island while the Gulf of Edremit-Ayvacık earthquake (M
S = 6.8) largely affected the northern and eastern coastal areas of the Gulf of Edremit. In 1944 earthquake, numerous surface
cracks and water gushes were reported. The coastal neighborhoods of the town of Ayvalık in the east were flooded by tsunami
waves. At the WSW extend of the main fault observed on land, which is parallel to the present-day slip vectors, some normal-oblique
faults were observed close and subparallel to the northern coast. On the basis of historical documents, reports, interviews,
geological setting, field observations and marine seismic reflection data, the 1944 earthquake was not triggered by one of
the main fault segments but by a secondary fault or fault group which was described in this study. Depending on the distribution
of tensional and compressional forces in the region, which rotates clockwise under the control of the middle strand of the
North Anatolian fault, secondary fault groups become important. The moment tensor parameters of such small-size events have
been determined and have obtained consistent results with the faults proposed in this study. 相似文献
23.
Altan Baykal Ça&#;da&#; &#;nam M. Ali Alpar Jean in 'T Zand Tod Strohmayer 《Monthly notices of the Royal Astronomical Society》2001,327(4):1269-1272
Using X-ray data from the Rossi X-ray Timing Explorer , we report the pulse timing results of the accretion-powered, high-mass X-ray binary pulsar 4U 1907+09, covering a time-span of almost two years. We measured three new pulse periods in addition to the previously measured four pulse periods. We are able to connect pulse arrival times in phase for more than a year. The source has been spinning down almost at a constant rate, with a spin-down rate of for more than 15 yr. Residuals of pulse arrival times yield a very low level of random-walk noise, with a strength of ∼ on a time-scale of 383 d, which is 40 times lower than that of the high-mass X-ray binary pulsar Vela X-1. The noise strength is only a factor of 5 greater than that of the low-mass X-ray binary pulsar 4U 1626−67. The low level of the timing noise and the very stable spin-down rate of 4U 1907+09 make this source unique among the high-mass X-ray binary pulsars, providing another example, in addition to 4U 1626−67, of long-term quiet spin down from an accreting source. These examples show that the extended quiet spin-down episodes observed in the anomalous X-ray pulsars 1RXS J170849.0−400910 and 1E 2259+586 do not necessarily imply that these sources are not accreting pulsars. 相似文献
24.
The ability of artificial neural networks (ANN) to model the rainfall-discharge relationships of karstic aquifers has been
studied in the La Rochefoucauld karst system, south-west France, which supplies water to the city of Angoulême. A neural networks
model was developed based on MLP (multi-layer perceptron) networks and the Levenberg-Marquardt optimization algorithm. Raw
rainfall data were used without transformation into effective rainfall. This allowed for the elimination of certain non-verifiable
simplifying assumptions and their subsequent introduction into the modeling procedure. The raw rainfall and discharge data
were divided into three groups for the training, the validation and the prediction test of the ANN model. The training and
validation phases led to a very satisfactory calibration of the ANN model. The attempt to predict discharges showed that the
ANN model is able to simulate the karstic aquifer discharges. The shape of the simulated hydrographs was found to be similar
to that of the actual hydrographs. These encouraging results make it possible to consider interesting and new prospects for
the modeling of karstic aquifers, which are highly non-linear systems.
Resumen Se ha estudiado la capacidad de las redes artificiales neurales (ANN) para modelizar las relaciones de lluvia-descarga de acuíferos kársticos en el sistema kárstico La Rochefocauld, al suroeste de Francia, el cual abastece de agua a la ciudad de Angoulême. Se desarrolló un modelo de redes neurales en base a redes MLP (Perceptron Multi-Capas) y el algoritmo de optimización Levenberg-Marquardt. Se utilizaron datos de lluvia sin la transformación hacia lluvia efectiva. Esto permitió la eliminación de ciertos supuestos simplificadores no verificables y su subsiguiente introducción en el procedimiento de modelizado. Los datos brutos de descarga y lluvia se dividieron en 3 grupos para la preparación, validación y la prueba de predicción del modelo ANN. Las fases de preparación y validación llevaron a una calibración muy satisfactoria del modelo ANN. El intento por predecir descargas mostró que el modelo ANN es capaz de simular las descargas del acuífero kárstico. Se encontró que la forma de los hidrogramas sintéticos es similar a la de los hidrogramas reales. Estos resultados alentadores hacen posible considerar prospectos nuevos e interesantes para el modelizado de acuíferos kársticos los cuales son sistemas altamente no-lineares.
Résumé L’aptitude des réseaux de neurones artificiels (RNA) à modéliser les relations pluie-débit des aquifères karstiques a été évaluée sur le karst de La Rochefoucauld (Sud-Ouest de la France), qui fournit l’eau potable à la capitale régionale Angoulême. Un modèle RNA a été développé à cet effet, basé sur les réseaux PMC (Perceptron Multicouche) et l’algorithme d’optimisation de Levenberg-Marquardt. Les données de pluie utilisées concernent la pluie brute, sans transformation en pluie efficace, ce qui permet de s’affranchir de certaines hypothèses simplificatrices non vérifiables. Les données de pluie brute et de débit ont été réparties en 3 groupes pour l’apprentissage, la validation et le test de prédiction du RNA. Les phases d’apprentissage et de validation ont permis d’aboutir à une calibration très satisfaisante du modèle RNA. La tentative de prédiction a montré que le RNA est apte à simuler les débits de l’aquifère karstique à partir de la pluie brute. La forme des hydrogrammes simulés est semblable à celle des hydrogrammes réels. Les résultats obtenus sont très encourageants et permettent d’envisager des perspectives intéressantes et nouvelles de modélisation des aquifères karstiques, qui sont des systèmes hautement non-linéaires.相似文献
25.
Çağatay M. N. Görür N. Alpar B. Saatçılar R. Akkök R. Sakınç M. Yüce H. Yaltırak C. Kuşcu I. 《Geo-Marine Letters》1998,18(1):1-9
The Gulf of Saros is an Upper Miocene transtensional basin in NW Anatolia, formed by the interaction between the North Anatolian
Fault and the N-S extensional tectonic régime of the Aegean. The present configuration of the basin evolved mainly during
the Plio-Quaternary under the increased activity of the North Anatolian Fault. During the late Miocene-late Quaternary, no
sedimentation took place on the shelves. After this long hiatus, an important change in tectonic style about 0.2 Ma BP allowed
sedimentation to resume in the gulf.
Received: 14 February 1997 / Revision received: 12 November 1997 相似文献
26.
M. Ali Alpar 《Journal of Astrophysics and Astronomy》2017,38(3):44
G. Srinivasan et al. (1990) proposed a simple and elegant explanation for the reduction of the neutron star magnetic dipole moment during binary evolution leading to low mass X-ray binaries and eventually to millisecond pulsars: Quantized vortex lines in the neutron star core superfluid will pin against the quantized flux lines of the proton superconductor. As the neutron star spins down in the wind accretion phase of binary evolution, outward motion of vortex lines will reduce the dipole magnetic moment in proportion to the rotation rate. The presence of a toroidal array of flux lines makes this mechanism inevitable and independent of the angle between the rotation and magnetic axes. The incompressibility of the flux-line array (Abrikosov lattice) determines the epoch when the mechanism will be effective throughout the neutron star. Flux vortex pinning will not be effective during the initial young radio pulsar phase. It will, however, be effective and reduce the dipole moment in proportion with the rotation rate during the epoch of spindown by wind accretion as proposed by Srinivasan et al. The mechanism operates also in the presence of vortex creep. 相似文献