The polarization direction of fast wave and the delay time between fast and slow wave were measured for two earthquake sequences occurred continuously on 21 July （M=6.2） and 16 October （M=6.1） in Dayao, Yunnan in ...The polarization direction of fast wave and the delay time between fast and slow wave were measured for two earthquake sequences occurred continuously on 21 July （M=6.2） and 16 October （M=6.1） in Dayao, Yunnan in 2003 using cross-correlation coefficient method, after determining the high-resolution hypocentral locations of the earthquake sequences using the double-difference earthquake location algorithm. The results indicated that ① The phenomena of S wave splitting are obvious in the two earthquake sequences, and the average polarization directions of fast wave in most stations are almost consistent with regional maximum horizontal compressive stress direction except the station Santai. There are bimodal fast directions in the polarization directions at station Santai and the mean polarization direction is N80°E, indicating an inconsistent phenomenon referred to regional maximum horizontal compressive stress direction. ② There is no apparent relation between delay time and focal depth in the sequences, but the polarization direction show different character in different delay time range. ③ The comparison of S wave splitting results in the two earthquake sequences show that the polarization direction in M=6.2 earthquake sequence is more scattered and its average fast direction is 20° larger than that of M=6.1 sequence, and the delay times between two sequences show a little difference. ④ The spatial variation in S wave splitting polarization direction may be due to the stress disturbance imposed by the M=6.2 and the M=6.1 mainshocks on regional background stress field.展开更多
Aquifers can be defined as complex ecological systems. Their description is closely influenced by geometrical and geological parameters, which portray the hydrogeological behaviour of underground systems. This paper r...Aquifers can be defined as complex ecological systems. Their description is closely influenced by geometrical and geological parameters, which portray the hydrogeological behaviour of underground systems. This paper reports a con<span>tribution to assess</span></span><span style="font-family:"">ing</span><span style="font-family:""> groundwater contamination risk in a particular Sicily sector, where deterministic approaches have methodically assessed and mappe</span><span style="font-family:"">d vulnerability and quality of groundwater. In detail, in the coastal area of Acqued<span>olci (Northern Sicily), already intensely surveyed in the frame of interdisciplinary projects on geological risk, implementing models and systems ha</span>ve been experimented, also considering fuzzy logic. Cartography issues are he<span>re presented and compared, with particular regard to the effect of stoc</span>h<span>astic hydrogeo</span><span>logical elements (<i>i.e.</i> “depth to water”), locally characterized by variability for simultaneous climate, overdraft, irrigation and sea encroachm</span>ent. </span><span style="font-family:"">Th<span>e </span></span><span style="font-family:"">authors show how fuzzy logic, applied to vulnerability settings, contributes to a better comprehension of the passive scenery offered by aquifers in</span><span style="font-family:""> Acquedolci Sicily area.展开更多
基金National Program on Key Basic Projects (2004CB418406), Program for the Tenth Five-Year Plan of China(2004BA601B01-04-03)and Joint Seismological Science Foundation of China (606042).
文摘The polarization direction of fast wave and the delay time between fast and slow wave were measured for two earthquake sequences occurred continuously on 21 July （M=6.2） and 16 October （M=6.1） in Dayao, Yunnan in 2003 using cross-correlation coefficient method, after determining the high-resolution hypocentral locations of the earthquake sequences using the double-difference earthquake location algorithm. The results indicated that ① The phenomena of S wave splitting are obvious in the two earthquake sequences, and the average polarization directions of fast wave in most stations are almost consistent with regional maximum horizontal compressive stress direction except the station Santai. There are bimodal fast directions in the polarization directions at station Santai and the mean polarization direction is N80°E, indicating an inconsistent phenomenon referred to regional maximum horizontal compressive stress direction. ② There is no apparent relation between delay time and focal depth in the sequences, but the polarization direction show different character in different delay time range. ③ The comparison of S wave splitting results in the two earthquake sequences show that the polarization direction in M=6.2 earthquake sequence is more scattered and its average fast direction is 20° larger than that of M=6.1 sequence, and the delay times between two sequences show a little difference. ④ The spatial variation in S wave splitting polarization direction may be due to the stress disturbance imposed by the M=6.2 and the M=6.1 mainshocks on regional background stress field.
文摘Aquifers can be defined as complex ecological systems. Their description is closely influenced by geometrical and geological parameters, which portray the hydrogeological behaviour of underground systems. This paper reports a con<span>tribution to assess</span></span><span style="font-family:"">ing</span><span style="font-family:""> groundwater contamination risk in a particular Sicily sector, where deterministic approaches have methodically assessed and mappe</span><span style="font-family:"">d vulnerability and quality of groundwater. In detail, in the coastal area of Acqued<span>olci (Northern Sicily), already intensely surveyed in the frame of interdisciplinary projects on geological risk, implementing models and systems ha</span>ve been experimented, also considering fuzzy logic. Cartography issues are he<span>re presented and compared, with particular regard to the effect of stoc</span>h<span>astic hydrogeo</span><span>logical elements (<i>i.e.</i> “depth to water”), locally characterized by variability for simultaneous climate, overdraft, irrigation and sea encroachm</span>ent. </span><span style="font-family:"">Th<span>e </span></span><span style="font-family:"">authors show how fuzzy logic, applied to vulnerability settings, contributes to a better comprehension of the passive scenery offered by aquifers in</span><span style="font-family:""> Acquedolci Sicily area.
