On April 20, 2013, the Lushan M^7.0 earthquake struck at the southern part of the Longmenshan fault in the eastern Tibetan Plateau, China. The shear-wave splitting in the crust indicates a connection between the direc...On April 20, 2013, the Lushan M^7.0 earthquake struck at the southern part of the Longmenshan fault in the eastern Tibetan Plateau, China. The shear-wave splitting in the crust indicates a connection between the direction of the principal crustal com- pressive stress and the fault orientation in the Longmenshan fault zone. Our relocation analysis of the aftershocks of the Lushan earthquake shows a gap between the location of the rupture zone of the Lushan Ms7.0 earthquake and that of the rup- ture zone of the Wenchuan MsS.0 earthquake. We believe that stress levels in the crust at the rupture gap and its vicinity should be monitored in the immediate future. We suggest using controlled source borehole measurements for this purpose.展开更多
A continuous GPS array across the southern segment of the Longmenshan fault zone recorded the deformation during the process of the Lushan MS7.0 earthquake that occurred on April 20, 2013. Such data can provide meanin...A continuous GPS array across the southern segment of the Longmenshan fault zone recorded the deformation during the process of the Lushan MS7.0 earthquake that occurred on April 20, 2013. Such data can provide meaningful information regarding the dynamic evolution of crustal deformation in the seismogenic zone. Our studies have shown that the occurrence of the Wenchuan earthquake led to the loading of compressive and sinistral shearing strain on the southern segment of the Maoxian-Wenchuan fault, whereby the extrusion strain accumulated at a greater rate than before the Wenchuan earthquake. The strain time series in the seismogenic zone revealed that the principal compression strain rates decreased from west to east in the direction of N30°–45°W. Furthermore, the area to the east of Beichuan-Yingxiu fault behaved as a zone of compressive deformation with obvious sinistral shearing deformation. The surface strain and the first shearing strain time series decreased with time, while the area to the west of the Beichuan-Yingxiu fault behaved as a zone of dextral shear deformation that increased with time. Furthermore, the regional deformation field before the Lushan earthquake showed that the rate of extrusion strain accumulation in the southern segment of the Longmenshan fault zone was obviously larger than before the Wenchuan earthquake. Moreover, the sinistral shearing strain accumulated in the area of the southern segment of the Maoxian-Wenchuan fault. Based on the above analysis, we consider that the eastward movement of the Bayan Har block increased considerably following the Wenchuan earthquake, which enhanced the accumulation of compression strain in the southern segment of the Longmenshan fault zone.展开更多
Processes of adaptation to urban environments are well described for relatively few avian taxa, mainly passerines, but selective forces responsible for urban colonization in ecologically different groups of birds rema...Processes of adaptation to urban environments are well described for relatively few avian taxa, mainly passerines, but selective forces responsible for urban colonization in ecologically different groups of birds remain mostly unrecognized. The aim of this article is to identify drivers of recent urban colonization （Lodz, central Poland） by a reed-nesting waterbird, the Eurasian coot Fulica atra. Urban colonizers were found to adopt a distinct reproductive strategy by maximizing the number of offspring （carryover effects of higher clutch size）, whereas suburban individuals invested more in the quality of the progeny （higher egg volume）, which could reflect differences in predatory pressure between 2 habitats. In fact, reduced predation rate was strongly suggested by elevated hatching success in highly urbanized areas, where probability of hatching at least 1 chick was higher by 30% than in suburban natural-like habitats. Coots nesting in highly urbanized landscape had considerably higher annual reproductive success in comparison to suburban pairs, and the difference was 4-fold between the most and least urbanized areas. There was also a constant increase in size- adjusted body mass and hemoglobin concentration of breeding coots from the suburbs to the city centre. Urban colonization yielded no survival benefits for adult birds and urban individuals showed higher site fidelity than suburban conspecifics. The results suggest that the recent urban colonization by Eurasian coots was primary driven by considerable reproductive benefits which may be primarily attributed to： （1） reduced predation resulting from an exclusion of most native predators from highly urbanized zones; （2） increased condition of urban-dwelling birds resulting from enhanced food availability.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41174042, 41040034)the China National Special Fund for Earthquake Scientific Research in Public Interest (Grant No. 201008001)
文摘On April 20, 2013, the Lushan M^7.0 earthquake struck at the southern part of the Longmenshan fault in the eastern Tibetan Plateau, China. The shear-wave splitting in the crust indicates a connection between the direction of the principal crustal com- pressive stress and the fault orientation in the Longmenshan fault zone. Our relocation analysis of the aftershocks of the Lushan earthquake shows a gap between the location of the rupture zone of the Lushan Ms7.0 earthquake and that of the rup- ture zone of the Wenchuan MsS.0 earthquake. We believe that stress levels in the crust at the rupture gap and its vicinity should be monitored in the immediate future. We suggest using controlled source borehole measurements for this purpose.
基金supported by the National Natural Science Foundation of China(Grant Nos.41274008,41104004)the Basic Research Project of Institute of Earthquake Science of China Earthquake Administration(Grant No.2014IES010101)
文摘A continuous GPS array across the southern segment of the Longmenshan fault zone recorded the deformation during the process of the Lushan MS7.0 earthquake that occurred on April 20, 2013. Such data can provide meaningful information regarding the dynamic evolution of crustal deformation in the seismogenic zone. Our studies have shown that the occurrence of the Wenchuan earthquake led to the loading of compressive and sinistral shearing strain on the southern segment of the Maoxian-Wenchuan fault, whereby the extrusion strain accumulated at a greater rate than before the Wenchuan earthquake. The strain time series in the seismogenic zone revealed that the principal compression strain rates decreased from west to east in the direction of N30°–45°W. Furthermore, the area to the east of Beichuan-Yingxiu fault behaved as a zone of compressive deformation with obvious sinistral shearing deformation. The surface strain and the first shearing strain time series decreased with time, while the area to the west of the Beichuan-Yingxiu fault behaved as a zone of dextral shear deformation that increased with time. Furthermore, the regional deformation field before the Lushan earthquake showed that the rate of extrusion strain accumulation in the southern segment of the Longmenshan fault zone was obviously larger than before the Wenchuan earthquake. Moreover, the sinistral shearing strain accumulated in the area of the southern segment of the Maoxian-Wenchuan fault. Based on the above analysis, we consider that the eastward movement of the Bayan Har block increased considerably following the Wenchuan earthquake, which enhanced the accumulation of compression strain in the southern segment of the Longmenshan fault zone.
文摘Processes of adaptation to urban environments are well described for relatively few avian taxa, mainly passerines, but selective forces responsible for urban colonization in ecologically different groups of birds remain mostly unrecognized. The aim of this article is to identify drivers of recent urban colonization （Lodz, central Poland） by a reed-nesting waterbird, the Eurasian coot Fulica atra. Urban colonizers were found to adopt a distinct reproductive strategy by maximizing the number of offspring （carryover effects of higher clutch size）, whereas suburban individuals invested more in the quality of the progeny （higher egg volume）, which could reflect differences in predatory pressure between 2 habitats. In fact, reduced predation rate was strongly suggested by elevated hatching success in highly urbanized areas, where probability of hatching at least 1 chick was higher by 30% than in suburban natural-like habitats. Coots nesting in highly urbanized landscape had considerably higher annual reproductive success in comparison to suburban pairs, and the difference was 4-fold between the most and least urbanized areas. There was also a constant increase in size- adjusted body mass and hemoglobin concentration of breeding coots from the suburbs to the city centre. Urban colonization yielded no survival benefits for adult birds and urban individuals showed higher site fidelity than suburban conspecifics. The results suggest that the recent urban colonization by Eurasian coots was primary driven by considerable reproductive benefits which may be primarily attributed to： （1） reduced predation resulting from an exclusion of most native predators from highly urbanized zones; （2） increased condition of urban-dwelling birds resulting from enhanced food availability.
