Transverse architecture of lahar terraces,inferred from radargrams: preliminary results from Semeru Volcano,Indonesia

Semeru Volcano is the highest mountain of Java (Indonesia), and a vulcanian explosion occurs every 15 minutes on average, since 1967. Thus a constantly renewed stock of material and the heavy monsoon rainfall [3700 mm yr^?1 at 1500 m above sea level (a.s.l.)] provide a perfect setting for the study of lahars and their deposits. Hence, we examined the architecture of lahars' terraces 9·5 km from the summit in the Curah Lengkong Valley. We first used ground penetrating radar (GPR) over vertical exposures of the lahars cut‐bank terraces. This allowed us to better understand transversal radargrams across terraces, which are not visually accessible in the field. Preliminary results from a single radargram are very instructive, since (1) they prove that the lateral architecture does not correspond to that observed from banks only; (2) we could observe the presence of lenses and stratigraphic discontinuities; (3) the setting of the various units can also help reconstruct deposition processes and the chronology of different units. In order to finalize these preliminary results, we however need to perform multiple GPR radargrams and provide a complete set of results. Copyright © 2010 John Wiley & Sons, Ltd.     

Color variations of the blazar 3C 454.3 in 2004–2006

We present an analysis of multicolor (U BV RI JH K) observations of the blazar 3C 454.3 made in 2004–2006. We used the light curves compiled at the Turin Observatory from coordinated observations in the framework of the WEBT program. We consider color variations in two time intervals, when an unprecedented strong outburst occurred (2004–2005), and when the object was in a post-eruptive state and a low-amplitude brightness increase was observed (2006). The spectral energy distribution (SED) of the variable component remained the same within each of these intervals, but differed between them. In both cases, this SED followed a power law after correction for extinction, suggesting the variable component has a synchrotron nature. We conclude that the variations in the optical and IR were due to the same variable source. The object’s unusual color behavior (the brighter, the redder) was due to an increasing contribution from a variable component that was redder than the constant component (big blue bump).     

Longitudinal structure of pyroclastic-flow deposits,revealed by GPR survey,at Merapi Volcano,Java, Indonesia

In 2006 Merapi volcano, Indonesia, erupted for a few months, producing several block-and-ash flows reaching a maximum distance of 7.5 km from the main vent. During the eruption, we conducted a survey on those flow deposits in the Gendol Valley at Kaliadem village, about 4.5 km from the Merapi submit, using a Ground Penetrating Radar (GPR). The upper deposit was studied in its distal reaches, whereas the one below was studied in its medial reaches. The field study was carried out with a commercial RAMAC® GPR coupled with 100 MHz antennas, and the data treatment conducted with Reflex™ software. From this survey, we determined both deposits' local (1) thickness – reaching a maximum of 15 m – and (2) internal architecture. This last one is governed by long reflecting horizons extending over 20 to 30 m that delimit layers showing progradation patterns in their distal reaches. Within these layers we could also observe an internal architecture of still unknown origin. The layers are interpreted as the result of the flow pulses that progressively deposited downstream-ward by progradation. However the interpretation of those GPR profiles is a bit hazardous, because of the absence of outcrops, and we can only proceed by analogy with other studies. Nevertheless, despite numerous limitations, GPR is a helpful tool to understand pyroclastic deposits' structure when no visual observations are available.     

Orbital forcing and role of the latitudinal insolation/temperature gradient

Orbital forcing of the climate system is clearly shown in the Earths record of glacial–interglacial cycles, but the mechanism underlying this forcing is poorly understood. Traditional Milankovitch theory suggests that these cycles are driven by changes in high latitude summer insolation, yet this forcing is dominated by precession, and cannot account for the importance of obliquity in the Ice Age record. Here, we investigate an alternative forcing based on the latitudinal insolation gradient (LIG), which is dominated by both obliquity (in summer) and precession (in winter). The insolation gradient acts on the climate system through differential solar heating, which creates the Earths latitudinal temperature gradient (LTG) that drives the atmospheric and ocean circulation. A new pollen-based reconstruction of the LTG during the Holocene is used to demonstrate that the LTG may be much more sensitive to changes in the LIG than previously thought. From this, it is shown how LIG forcing of the LTG may help explain the propagation of orbital signatures throughout the climate system, including the Monsoon, Arctic Oscillation and ocean circulation. These relationships are validated over the last (Eemian) Interglacial, which occurred under a different orbital configuration to the Holocene. We conclude that LIG forcing of the LTG explains many criticisms of classic Milankovitch theory, while being poorly represented in climate models.     

Simple Model of a Stochastically Excited Solar Dynamo

The aim of this paper is to investigate the dynamical nature of the complexity observed in the time evolution of the sunspot number. We report a detailed analysis of the sunspot number time series, and use the daily records to build the phase space of the underlying dynamical system. The observed features of the phase space prompted us to describe the global behavior of the solar cycle in terms of a noise-driven relaxation oscillator. We find the equations whose solutions best fit the observed series, which adequately describe the shape of the peaks and the oscillations of the system. The system of equations obtained from this fitting procedure is shown to be equivalent to a truncation of the dynamo equations. A linear transformation maps the phase space of these equations into the phase space reconstructed from the observations. The irregularities of the solar cycle were modeled through the introduction of a stochastic parameter in the equations to simulate the randomness arising in the process of eruption of magnetic flow to the solar surface. The mean values and deviations obtained for the periods, rise times and peak values, are in good agreement with the values obtained from the sunspot time series.     

Integrated remote sensing and GIS techniques for biogeochemical characterization of the Tinto-Odiel estuary system,SW Spain

The Tinto-Odiel estuary area in SW Spain presents a high concentration of industrial, agricultural and mining activities that seriously affect water quality, producing significant concentrations in trace metals and other contaminant elements. Previous studies have highlighted the important environmental effect of these contaminated waters discharged into the Gulf of Cadiz, contributing in a marked way to trace-metal concentrations in the Mediterranean Sea by water inflow through the Strait of Gibraltar. A global biogeochemical characterization of these waters was the main objective of a multidisciplinary research study funded by the European Union, in which remote sensing and GIS techniques, among other methodologies, were jointly applied. The main results confirmed the usefulness of this integrated methodological approach as an effective tool for the assessment of current biogeochemical conditions. Digital image processing provided valuable thematic information for temporal hydrodynamic analysis and water quality parameters mapping, which was integrated into a GIS database together with experimental information sampled in oceanographic cruises.     

New perspective about the existence of a supermassive black hole in a quasar with double redshift systems

Research of several years has confirmed the general aspect that the most acceptable model in quasars' nuclei is a rotating Kerr black hole.Assuming the Kerr type potential given by the equation:

Environmental impact assessment using FORM and groundwater system reliability concept: case study Jining, China

In this paper, fist-order reliability method (FORM) is used to evaluate the impacts of uncertainties posed by traditional deterministic models on the environment in Jining, China. Because of groundwater contamination in shallow aquifer, and an increase in water demand, the new wells target the confined aquifer with constant pumping rate of 5,000 m³/d. Using Theis equation, the groundwater drawdown is analyzed to determine whether the confined aquifer will be contaminated. Although the piezometric level is higher than the phreatic level by 11.0 m, the risk of drawdown is still 19.49% when the pumping rate of 5,000 m³/d is maintained for 2 years. The deterministic model indicates a drawdown of 8.94 m which is lower than the maximum tolerance drawdown of 11.0 m. The sensitivity and uncertainty analysis reveal that the model result is more sensitive to transmissivity than specific yield, while the reliability analysis offers significant information for the decision makers. This approach exposes and minimizes the risk of undesirable consequences such as groundwater contamination.     

A preliminary study of the relationship between large earthquakes and precipitation for the region of Athens,Greece

The annual rainfall data of Athens rain gauge stations, for the last 119 years, is compared with the occurrence of large (M 6) earthquakes along the fault and thrust systems in the vicinity of Athens and interesting correlations have been observed.This preliminary investigation reveals the possible occurrence of a large earthquake in the region of Athens till 1993.