Correspondence analysis applied to volcanic aerosols

A statistical analysis of volcanic aerosol based on 1,083 variables including concentration, grain-size and site variabilities establishes correlations between sites and among chemical elements.Variation curves of element concentration show parallel behaviour. High coefficients of correlation between anions and cations confirm associations between elements.     

Phosphorus accumulation rates in metalliferous sediments on the East Pacific Rise

Based on phosphorus, iron and manganese analyses in 16 cores (5 dated) from the crest and flanks of the East Pacific Rise and the Bauer Deep we estimate that phosphorus is being deposited about 20 times faster in metalliferous sediments near the rise crest than in adjacent flank deposits, and about 40 times faster on the crest than in the Bauer Deep. Almost all of the phosphorus on the rise crest is contained in poorly crystallized hydrothermal iron oxyhydroxides, supporting Berner's (1973) proposal of phosphate sorption by these phases. The phosphate is probably derived from seawater, but some hydrothermal contribution cannot be excluded at this time. Flux estimates indicate that metalliferous sedimentation could remove 15–40% of the pre-agricultural river input of dissolved phosphate.     

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MINI-SOSIE FOR LAND SEISMOLOGY*

Mini-sosie consists in using a vibration-rammer as seismic source and changing the striking rate by varying the engine speed, resulting in a random impulse transmission. The recording instruments are made up of two seismic traces, two constant gain amplifiers and a two-channel sosie processor which performs the decoding in real time by using the actual transmission times supplied by a captor located on top of the vibration-rammer's plate. An idea of the possible penetration is given by the recording of a velocity survey. Other results obtained in seismic reflection and refraction are given.     

Fractional Tajimi–Kanai model for simulating earthquake ground motion

The ground acceleration is usually modeled as a filtered Gaussian process. The most common model is a Tajimi–Kanai (TK) filter that is a viscoelastic Kelvin–Voigt unit (a spring in parallel with a dashpot) carrying a mass excited by a white noise (acceleration at the bedrock). Based upon the observation that every real material exhibits a power law trend in the creep test, in this paper it is proposed the substitution of the purely viscous element in the Kelvin Voigt element with the so called springpot that is an element having an intermediate behavior between purely elastic (spring) and purely viscous (dashpot) behavior ruled by fractional operator. With this choice two main goals are reached: (i) The viscoelastic behavior of the ground may be simply characterized by performing the creep (or the relaxation) test on a specimen of the ground at the given site; (ii) The number of zero crossing of the absolute acceleration at the free field that for the classical TK model is \(\infty \) for a true white noise acceleration, remains finite for the proposed model.     

Long-term seismological sea-bottom monitoring using autonomous bottom stations

Merits and demerits of recording of seismic signals at the bottom of water areas are considered. It is shown that long-term seismological monitoring systems should be placed in the regions of industrial development of the shelf and continental slope and in the areas of high seismic and tsunami hazard of oceans and seas. The results obtained during expeditions of the Shirshov Institute of Oceanology of the Russian Academy of Sciences with the use of broadband bottom seismographs are reported. Autonomous bottom seismographs with long-term operation at the bottom and operative communication via satellite and radio channels are proposed for the formation of a marine seismological network.     

Thunderstorm activity according to VLF observations at Kamchatka

The azimuthal distribution of lightning discharges and cyclone epicenters at a distance of up to 4000 km from the observation point at Kamchatka is given. The azimuths of lightning discharges were determined using an ELF finder, and the cyclone epicenters were determined from meteorological maps. Time dependences of the distribution of received radiations from lightning discharges have been obtained.