Early Flows Research Articles

Immigration to Western Europe, 1952-1982: a time-series analysis of movement to Sweden, France, and Essen.

"Two contradictory approaches--an equilibrium view based on neoclassical economic principles and a structuralist view based on labour needs of core economies--dominate contemporary international migration research. Using a monthly time-series for Essen [Federal Republic of Germany], Sweden, and France for 1952-1982 of immigration by different nationalities, a specific hypothesis derived from the neoclassical view, relating immigration to economic growth and stagnation, was tested using the Box-Jenkins ARIMA modelling approach." The only support for the hypothesis came from the example of the local labor market in Essen. The author notes that "most migration flows are described by complex ARIMA models. Immigration legislation had a stronger and more direct effect on the strength and timing of flows than economic trends. Predictions based on univariate and bivariate models are not very useful: immigration trends over the past decade are significantly different from earlier flows."

Geology of the Volcan Chico Area on Sierra Negra Volcano, Galapagos Islands

Recent eruptions of Sierra Negra, a basaltic shield volcano, have been along fissure zones circumferentially oriented around the northern side of the caldera near the volcano summit. Two fissure zones, the Caldera Rim fissure and the Volcan Chico fissure, have produced more than 85 percent of the lava exposed on the north side of the volcano. Radial fissures are not common on this portion of Sierra Negra, and they have contributed only minor amounts of lava and pyroclastic material. Most of the recent activity has been localized along the broad zone of the Volcan Chico fissure, in areas of previous fumarolic activity. In 1963 an initial explosive phase produced a thin, widespread blanket of frothy pumice that was followed by the formation of agglutinate cones and voluminous lava flows. Late-stage slumping occurred and fumarolic activity continues. The well-defined Caldera Rim fissure has been the locus of caldera collapse in the Volcan Chico area; to the west it forms an eruptive zone along the caldera rim. This fissure zone has been the source of surface lava flows between the Volcan Chico fissure and the present caldera. The area between the two major fissure zones has not been a source area for eruptions or fumarolic activity. This area does include several linearly arranged collapse depressions that imply subsurface magmatic activity. The exposures of thick, massive, widespread flows, at shallow depths in the depressions and in the caldera walls, have two important implications: (1) These earlier flows had sources that were located within the present caldera previous to its collapse along the Caldera Rim fissure, and (2) later activity has not contributed significantly to the construction of the rim of Sierra Negra. The features examined in the Volcan Chico area are typical of Sierra Negra9s recent activity and indicate the mechanisms of volcano growth and caldera development late in the history of a Galapagos volcano.

Products of submarine slides and collapse in volcanic-sedimentary Goytkh series (northwestern Caucasus)

Laying down of graded argillaceous sediments with stringers of tuffites and tuffaceous sandstones was followed by the formation of tuffaceous claystone conglomerates in the Goytkh volcanic sedimentary series, while at the same time coarse elastic products of the cordillera disintegration were piling up in littoral zones to the northwest. The equilibrium of this accumulation was disturbed, probably by earthquakes, which set in motion huge volumes of elastic and volcanic material. Tuffaceous claystone conglomerates were deposited over a considerable bottom area as the current slowed down, only to be overlain by argillites, tuffites and tuffaceous sandstones brought along by the suspension currents which followed quiescent sedimentation periods. Second generation inclusions resulted from the moving density current which carried with it both the fresh deposits and those fragments and chunks left behind by earlier flows - a kind of “cannibalism” not uncommon in these regions.--IGR Staff