The volcano of Capelinhos (Azores), the solar activity and the earth-tide

Bulletin of Volcanology - Correlations on the eruptive behaviour of the volcano of Capelinhos (Fayal island) in 1957–58, with (a) solar activity, and (b) earth-tide amplitudes, by way of a...     

The submarine volcano of Capelinhos and the tectonics of the Azores

Bulletin of Volcanology - In another paper of the author, a picture of the tectonics of the Azores was presented. The morphological analysis showed evidence of a folded and faulted structure and...     

On the sunspot cycle and the yearly variation of solar magnetic variation at istanbul

Summary The sunspot cycle variation of the amplitude of the solar magnetic variation has been investigated for magnetically moderate, quiet and disturbed days at Istanbul for the period 1949–1968, and fairly good linear relationship has been found forZ andD components of the earth's magnetic field. In some cases, it is rather difficult to say that there is any linear relationship between sunspot number and the amplitude of theH component of the earth's magnetic field. Meanwhile,K indices has also been considered with sunspot number by means of multiple regression analysis to overcome some uncertainties in this investigation.     

Annual variation of the geomagnetic field

Summary. Horizontal and vertical intensity data, obtained between 1957.0 and 1961.0 at 69 observatories, are analysed to determine the worldwide distribution of the annual variation of the geomagnetic field. Only data observed near local midnight are used, to avoid the small, but significant contamination from Sq. Over most of the world the variation is found to be small, with a clear dependence on latitude, but near the poles it is larger and more erratic. The non-polar variation is subjected to spherical harmonic analysis and separated into parts of internal and external origin. The polar variations are shown to be consistent with a north—south oscillation of the mean position of the auroral electrojets during the year. It is suggested that, with the exception of the polar effect, the annual variation is not due to ionospheric currents (as was hitherto believed), but results from an annual variation in the latitude of the ring current.     

Monitoring of fault healing after the 1999 Kocaeli, Turkey, earthquake

The North Anatolian fault zone that ruptured during the mainshock of theM 7.4 Kocaeli (Izmit) earthquake of 17 August 1999 has beenmonitored using S wave splitting, in order to test a hypothesisproposed by Tadokoro et al. (1999). This idea is based on the observationof the M 7.2 1995 Hyogo-ken Nanbu (Kobe) earthquake, Japan.After the Hyogo-ken Nanbu earthquake, a temporal change was detectedin the direction of faster shear wave polarization in 2–3 years after the mainshock (Tadokoro, 1999). Four seismic stations were installed within andnear the fault zone at Kizanlik where the fault offset was 1.5 m, about80 km to the east of the epicenter of the Kocaeli earthquake. Theobservation period was from August 30 to October 27, 1999. Preliminaryresult shows that the average directions of faster shear wave polarization attwo stations were roughly parallel to the fault strike. We expect that thedirection of faster shear wave polarization will change to the same directionas the regional tectonic stress reflecting fault healing process. We havealready carried out a repeated aftershock observation at the same site in2000 for monitoring the fault healing process.     

Determination of source and palaeoclimate from the comparison of grain and clay fractions in sandstones: A case study

The Paleogene Ke?an Formation of southwestern Turkish Thrace (Alpine Ergene basin) which is dominantly a sandy facies, comprises the Çinarlidere (Lower) and ?aplidere (Upper) members. The turbidite sandstones of the Formation are petrologically defined as multicycle, moderately sorted, angular to subrounded, coarse-skewed, submature graywackes with a detrital clayey matrix of over 15%.The quantitative analyses of light, heavy and clay fractions of sandstone samples from the Ke?an Formation showed marked petrographic variations with grouping of these sediments as Lower- and Upper-member mineralogical facies and led to the following conclusions: a southern terrain with a relatively warm and tropical climate on a terrestrial source of a peneplain topography provided detrital material for the Lower-member sediments (the Biga Massif), while the Upper-member sediments were derived from a rapid erosion of an area of high relief with a uniform supply and continuous infilling of the basin of deposition (a western source terrain: the Rhodope Massif).     

Relations entre les données isotopiques océaniques et l'histoire des grandes faunes européennes plio-pleistocenes

This study is the first test of correlation between the results obtained on the large Plio-Pleistocene European faunas and the main climatic stages (cold as well as temperate) demonstrated in marine isotopic records. In particular, there are cold stages which often explain the disappearance of some species, as well as climatic events that promote the substitution of some species by other groups. A rather evident parallelism appears between the European succession of large faunal associations and paleoclimatic stages revealed in oceanic areas, but some discordance occurs in the later periods. Faced with the great diversification of the Quaternary faunas, probably due to the multiplicity of climatic environments, and with global information from oceanic records, only local biostratigraphic studies will allow precise reconstruction of the different biotopes.     

Twenty Years Seismic Monitoring of Induced Seismicity in Northern Albania

—The northern part of Albania has been the focus of an intense effort by the Seismological Institute of Albania, for in this area two of the country’s biggest reservoirs are located. Three years before the impounding of the Fierza reservoir, a four-station network was installed around it. The possibility of induced seismicity continued after the impoundment of the Fierza reservoir in 1978 and the Komani reservoir, in 1985. The seismicity of the zone and some aspects of induced seismicity including temporal correlation of seismicity with water level changes, spatial patterns in seismicity, frequency-mag nitude relations, fault plane solutions etc., are studied during this period. The presence in this zone of a very important transverse fault, the Shkoder-Peja fault, makes the study of induced seismicity from Fierza and Komani reservoirs even more significant. The studies have shown that the impounding of the Fierza and Komani reservoirs has modified the natural course of microearthquake energy release, increasing the number of swarms in this area.¶The fluctuation of the water level in these two reservoirs, in due course, is a potentially important factor in the evaluation of seismicity for Northern Albania and especially in the hazard assessment of this region.