Measuring the speed of gravity at short distances: Sensitivity estimate

An experimental set up was proposed to determine the speed of gravitational signals traveling in air or in some other medium. It involves two vibrating masses—the emitters, which will be the sources of periodic tidal gravitational signals—and one sapphire-made mass that will act as a detector, positioned between the two emitters. The detector is planned to be suspended in vacuum and cooled down to 4.2 K, and its vibrational amplitude should be measured by a microwave signal (with ultra-low phase-noise) that is expected to resonate with the whispering gallery modes inside the detector. The mechanical and electrical quality factors of sapphire are quite high, yielding a very narrow detection band that reduces the detector sensitivity while amplifying the phase difference of the emitters' signals. The frequencies of the normal modes of the detector were previously determined using a finite element program. In this work, these frequencies are applied to the calculation of a first estimate of the sensitivity of the experiment.     

SANARIS Project: A Satellite Network for Natural Risk Monitoring

A new satellite communication system specificallydesigned for low-rate data applications has beendeveloped and prototyped. A validation project isproposed to install a pilot network to be operated for6 months. One of the target markets related tovolcanoes, has been selected, so that a group of usersis integrated in the project. A specific applicationfor this market will be developed regarding dataacquisition, processing, storage and dissemination todistant users. The feasibility of using the newsatellite system to provide a new Eutelsat service forlow-rate data applications, will be evaluated from theperformance of the pilot network. The system ofautomatic acquisition, field storage and communicationwith the local control center is already functioning,as well as the circulation of information viaInternet. The development of the application andtransmission via satellite to distant users is stillin an evaluation phase for the volcanoes of Timanfaya(Lanzarote, Canary Island), Vesuvius (Naples) and SeteCidades Caldera (Sao Miguel, Azores Islands).     

Neyman-Scott cluster model for daily rainfall processes in lower extremadura (Spain): Rainfall Generating Mechanisms

Summary A Neyman-Scott cluster model was fitted to the daily rainfall data recorded at the observatory of Badajoz (southwestern Spain) for the period 1901–1990. The data were previously homogenized. The goodness of the fit that indicated the daily rainfall process follows some Rainfall Generating Mechanism (RGM). Having decided on the criteria that a block of rainfall must fulfill to be considered as a RGM, a method was proposed to classify the days that belong to RGMs according to the 500 hPa and the surface topography. In this method each day is characterized by a string of 22 alphanumeric characters. From the subsequent analysis, the structure of the synoptic patterns associated with each RGM was deduced.With 3 Figures     

Inter-provincial migration in Spain: temporal trends and age-specific patterns

"This paper provides interpretation of the changing patterns of internal migration in Spain at the inter-provincial scale, and new analysis of age-specific migration during the 1980s using a 10% sample of anonymised records from the 1991 census. Schedules of age-specific gross migration rates are constructed and classified according to their shape and level relative to the national schedule, and the relationships between in-migration and out-migration rates are examined for four selected age groups to demonstrate how aggregate patterns of inter-provincial migration conceal a wide diversity of age specific experience."     

Scientific drilling reveals geochemical heterogeneity within the Ko’olau shield,Hawai’i

The Koolau Scientific Drilling Project (KSDP) was initiated to determine if the distinctive geochemistry of Koolau lavas is a near-surface feature. This project successfully deepened a recent, ~351 m deep, tri-cone rotary-drilled water well by coring another ~328 m. Three Ar–Ar plateau ages of 2.8 to 2.9 Ma from the drill core section of 103 flows confirm stratigraphic interpretations that core drilling recovered the deepest and oldest subaerially erupted lavas yet sampled from this volcano. The petrography and geochemistry of the core, and cuttings from this and another new Koolau water well (~433 m deep) were determined. These analyses revealed that the geochemically distinct lavas of Koolau form a veneer only 175–250 m thick at the drill sites, covering flows with more typical Hawaiian tholeiite compositions. The compositional change occurred near the end of shield volcanism and is not abrupt. Thus, it is probably not related to a catastrophic event such as the collapse of the northeast flank of this volcano. The distinct geochemistry of surface Koolau lavas cannot be explained by melting pyroxenitic or combined pyroxenitic and peridotitic sources. Additional recycled oceanic crustal components, such as plagioclase-rich cumulates and sediment, were probably involved. As the Koolau volcano drifted off the Hawaiian hotspot and the overall degree of melting decreased, the proportion of melts from recycled oceanic crustal material increased relative to those from mantle peridotite.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.Editorial responsibility: T.L. Grove     

The Gleissberg Cycle of Minima

In this short article we show that the sunspot cycle minima exhibit a long cycle (Gleissberg) in addition to the 11-yr cycle. From 1750 onwards, three periods of the Gleissberg cycle can be detected.     

Geochemical and Isotopic Evolution of Loihi Volcano, Hawaii

The Publishers wish to apologise for the incorrect representationof figure 10 which accompanied this paper. The correct figureis reproduced below.     

Volatiles in pillow rim glasses from Loihi and Kilauea volcanoes,Hawaii

Volatiles and major elements in submarine glasses from Loihi seamount and Kilauea volcano. Hawaii were analyzed by high temperature mass spectrometry and the electron microprobe. Loihi glasses are subdivided into three groups: tholeiitic, transitional and alkali basalts. The glasses are evolved: Mg numbers range from 48–58. The alkalic lavas are the most evolved.Total volatiles range from 0.73 to 1.40 wt.%. H₂O shows a positive linear correlation with K₂O content [H₂O = 0.83 (± .09) K₂O + 0.08 (± .06)]. Concentrations of H₂O are higher in the alkalic lavas, but Cl and F abundances are highly variable. Variations in ratios of incompatible elements (K₂O, P₂O₅, H₂O) indicate that each group was derived from a distinct source. CO₂ contents range from 0.05 to 0.19 wt.% but show no systematic correlation with rock type or Mg #. A well-defined decrease in glass CO₂ content with increasing vesicularity is shown by the alkalic lavas. CO₂ may have been outgassed from the tholeiitic and transitional magmas prior to eruption during storage in a shallow magma chamber. Reduced carbon species (CO and CH₄) were found in small amounts in most of the alkalic samples. Although the redox histories of Hawaiian lavas are poorly known, these new data indicate the presence of a reduced source for Loihi magmas.The Kilauea tholeiitic glasses are evolved (Mg # 48.3 to 55) and have higher H₂O contents (av. 0.54 wt.%) than Loihi tholeiites (av. 0.42 wt.%) at the same Mg # (~55). Cl is distinctly lower in Kilauea glasses (0.01 wt.%) compared to Loihi glasses (0.09 wt.%). The data indicate significant source differences for the two volcanoes, consistent with results of other geochemical studies.Loihi tholeiites have distinctly higher ³He/⁴He ratios than Kilauea tholeiites and are the highest measured in submarine basalts (KURZ et al., 1983). These high ratios have been used to invoke a primitive source for Loihi basalts. The high Cl content of these basalts, the highest we have ever measured in submarine basalts, may be a fingerprint of this primitive source, as previously noted for Icelandic basalts (Schillinget al. 1980).     

Energy release in solar flares

Team 2 of the Ottawa FLARES 22 Workshop dealt with observational and theoretical aspects of the characteristics and processes of energy release in flares. Main results summarized in this article stress the global character of the flaring phenomenon in active regions, the importance of discontinuities in magnetic connectivity, the role of field-aligned currents in free energy storage, and the fragmentation of energy release in time and space.Report of Team 2, Flares 22 Workshop, Ottawa, May 25–28, 1993.     

The use of GPR for characterizing underground weathered profiles in the sub-humid tropics

Ground penetrating radar (GPR) has been used as a tool to access information about ground subsurface features. Such information is very important for different types of studies, varying from those related to archeological research to those studying geological elements of bedrock. More recently, however, GPR has been increasingly applied to environmental studies, especially for soil research. This paper presents the results of an application of GPR for the study of weathered profiles. GPR was used to discover the degree of trustworthiness of the information on the ground subsurface through the interpretation of the results of the radar sections as well as the data collected from boreholes, which reached until 21 m. The results show a relatively high degree of details obtained by GPR, indicating the possibility of speeding up ground subsurface surveys related to geomorphological, geological, and pedological studies.