Short- and long-term monitoring of radon, thoron and carbon dioxide in soil-gas at Altos de pipe, Venezuela

We have measured radon and thoron activities in soil-gases since July 9, 1997 Cariaco earthquake (Mw=6.9) until the end of 2000. Carbon dioxide concentrations were also monitored between 1998–2000. The soil-gas was collected between 50–55 cm depths at two sampling points at Altos de pipe (Instituto Venezolano de Investigaciones Cientificas-IVIC) near Caracas, Venezuela. The radon and thoron measurements were performed daily employing radiation monitors with scintillation cells and the carbon dioxide was monitored with portable gas analyzers. Average weekly and monthly values were calculated and plotted for this three-four year period. In general, both the radon and carbon dioxide values showed sinusoidal trends due to seasonal changes. During the dry season the radon and carbon dioxide values decreased, while the radon activity was relative constant (flat) during the rainy season at one of the sampling points. Only two monthly radon values were seen to be anomalous in the graphs in respect to seven anomalous periods for the average weekly values. No anomalous periods were clearly seen for carbon dioxide. Finally, it was difficult to try to relate these radon anomalous periods with specific earthquakes due to the large number of minor earthquakes during these years, but it seem that the minor earthquake (Mb=5.9) of October 4, 2000 could be associated with the radon anomalous period in September, when there were no other minor earthquakes (Mb≥4.0). This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of the provenance of majolica ceramics from Europe by thermoluminescence employing principal components

Thermoluminescence data, obtained from majolica pottery after irradiation in the laboratory with gamma rays, were studied using the principal components technique to determine if the places of manufacture of this ceramic are differentiated one from another. A total of ten provenances in Holland, Spain and Italy was established by principal components. Six variables were used for the statistical analysis: the three glow-peaks positions, the relative intensity of the second peak to the first peak, the relative intensity of the third peak to the first peak, and the area under the glow curve.The precision for these parameters was about ± 5%, but the precision of the variables for a suite of standards was much higher. In addition, two groups of sherds collected in Latin America, and previously assigned to the provenances of Cataluna and Sevilla (Spain) by artistic criteria, were investigated in this study. All six samples of Cataluna agreed well with their previous assignment of provenance, but several of the samples assigned previously to Sevilla were not related unambiguously to this provenance, although they were with certainty excluded from other provenances.