An evidence of flare energy buildup and release related to magnetic shear and reconnection

We study series of homologous flares, observed in the active region NOAA 2372 by the HXIS on the Solar Maximum Mission and ground based observatories. Changes in the flare homology, particularly those related to the location of the hard X-ray emission, show clear correlation with the development of magnetic shear within the active region. Following our early study (Machado et al., 1983) we propose that magnetic shear and reconnection are necessary for high power energy release, but the former may not be a sufficient condition in an isolated magnetic loop. These results are discussed within the context of a broader study, in order to explore their generality.     

Secular variation of seismo-volcanic phenomena in the azores

By studying the past behaviour of Azorean volcanoes, sunspot and Earth tide correlations have been discovered, and may certainly help in prediction. Some evidence has also been found that buckling of the thin roof of magma chambers may be the mechanism responsible for the eruptions, including the accompanying seismic swarms. If this is the case, geodetic control of the adjacent regions will probably be decisive in forecasting future activity.     

Oceanic fissure eruptions,subvolcanic intrusions and volcanic magma Chambers

Rifting along the mid-Atlantic ridge seems to have been accompanied by fissure eruptions which flooded the ocean bottom. Locally these plateau lavas rose above sea level and erosion revealed plutonic bodies emplaced within them. There is also some evidence of shallow magma chambers feeding surface volcanism. All these facts can be conveniently interpreted by assuming fractional melting of the upper mantle, at depths below about 50 km, and a pulsation of the pressure, produced by a varying gravitation, which seems capable of squeezing the molten fraction and of fracturing the solid crust above. Magma chambers can then be formed, probably by subterranean cauldron subsidence of Scottish type, they can leed surface volcanoes and will eventually solidify as plutonic bodies. Phase changes of eclogite, possibly present in the oceanic upper mantle, could also explain the uplift of island platforms.     

Activity of the Atlantic volcanoes, 1947–1965

A remarkable sequence of volcanic eruptions were observed in the Atlantic, during the last 20 years: Hckla in 1947, La Palma in 1949, Fogo in 1951, Fayal in 1957, Tristan da Cunha in 1961, Askja in 1961, Surtsey in 1963 (and possibly San Jorge in 1964). The long-period components of the Earth tide seem to influence the eruptive epochs, acting as trigger-forces.     

Origin and depositional environment of the china clay deposits of south Kerala

Results of petrographic, mineralogic and granulometric studies of the sedimentary china clay deposits of Trivandrum district in south Kerala are discussed in terms of their origin and depositional environment. While mineralogic data indicate a khondalitic source for the kaolins as against the hitherto postulated leptynitic source, petrographic evidences suggest that most of the kaolinite were transported from the weathering crust and deposited. Granulometric data and SEM scanning of sand grains from the clays indicate their deposition in a fluvial/low energy littoral environment under conditions of subaqueous agitation.     

Synthetic scenario generation of monthly streamflows conditioned to the El Niño–Southern Oscillation: application to operation planning of hydrothermal systems

Stochastic Environmental Research and Risk Assessment - The Brazilian Interconnected Power System is hydro dominated and characterized by large reservoirs presenting multi-year regulation...     

Newly discovered reefs in the southern Abrolhos Bank,Brazil: Anthropogenic impacts and urgent conservation needs

The Abrolhos Bank is an area of high ecological, socio-economic importance and harbour the richest and most-extensive coral reefs in the South Atlantic. Here we report the discovery of shallow (12–25 m depth) reef complex with ten large biogenic structures, intermediate between the typical mushroom-shaped pinnacles of the northern Abrolhos Bank (17°–18° S) and the small patch reefs found on the central/southern coast of the Espírito Santo State (19°–20° S). The newly discovered reefs harbour a relatively rich and abundant reef community, with 73 fish and 14 benthic cnidarian species, including endangered and commercially important ones. We discuss on urgent needs of properly mapping and understanding the ecological functioning of this reef system. Information provided here is a baseline for future impact evaluations, particularly considering the recent worst environmental disaster of Brazil from a dam collapse in Doce river that affected the region.