Previous investigations have shown that the seismic response of slopes during the Wenchuan earthquake was highly variable. The present study tries to give an answer to the question: Which are the main factors affecti...Previous investigations have shown that the seismic response of slopes during the Wenchuan earthquake was highly variable. The present study tries to give an answer to the question: Which are the main factors affecting the seismic response degree of slopes? With the support of the China Geological Survey Bureau, we set 3 monitoring sections in Jiulong slope, Mianzhu city, China with the aim to record the site response of the slope during the affershoeks of the Wenehuan earthquake. After the Wenchuan earthquake, which happened on 12 May 2008, 30 aftershocks have been recorded in these monitoring points. We analyzed 11 records, with magnitudes ranging from ML = 4.6 to ML = 3.1. The amplification factors of the horizontal compound PGA and 3D compound PGA have been determined for the 3 points at different elevations on the slope. Results showed that the dynamic response of the slope on the earthquake was controlled by factors such as topography and the thickness of the Quaternary overburden.展开更多
Between 1850 and 1900, state geological surveys in the Midwest underwent an ideological shift by transforming from institutions based on applied science to those based on pure science. Three factors influenced this pr...Between 1850 and 1900, state geological surveys in the Midwest underwent an ideological shift by transforming from institutions based on applied science to those based on pure science. Three factors influenced this process: the acquisition of permanent status from state governments, the establishment of the USGS (United States Geological Survey), and the increase in regional professional scientific societies and publications in the Midwest. These factors aided in the transformation of research projects by state geologists. These projects grew more focused, of higher quality, and increased in number during this time-period. State governments still expected Midwestern geological surveys to meet the practical needs of their respective states as this transformation continued, but surveys complemented these goals with projects more closely related to pure science. This shift encouraged the research goals of surveys to investigate projects more closely related to pure scientific pursuits, and significantly aided in the growth of the earth sciences in the nineteenth Century and early twentieth Century.展开更多
Global land cover data products are key sources of information in understanding the complex interactions between human activities and global change. They play a critical role in improving performances of ecosystem, hy...Global land cover data products are key sources of information in understanding the complex interactions between human activities and global change. They play a critical role in improving performances of ecosystem, hydrological and atmospheric models. Three freely available global land cover products developed in the United States are popularly used by the scientific community. These include two global maps developed separately by the United States Geological Survey (USGS) and the University of Maryland (UMD) with NOAA Advanced Very High Resolution Radiometer ( AVHRR ) data, and one developed by Boston University with the EOS Moderate Resolution Imaging Spectroradiometer ( MODIS) data. They are compared with known land cover types at 250 available Fluxnet sites around the world. The overall accuracies are 37%, 36% and 42%, respectively for the USGS, UMD and Boston global land cover maps, Some future global land cover mapping strategies are suggested.展开更多
基金supported by National Natural Science Foundation of China (Grant No.41072231)China Geological Survey Bureau (Grant Nos 1212010914010 and 1212011220154)Program for Changjiang Scholars and Innovative Research Team in University" (Grant No. IRT0812)
文摘Previous investigations have shown that the seismic response of slopes during the Wenchuan earthquake was highly variable. The present study tries to give an answer to the question: Which are the main factors affecting the seismic response degree of slopes? With the support of the China Geological Survey Bureau, we set 3 monitoring sections in Jiulong slope, Mianzhu city, China with the aim to record the site response of the slope during the affershoeks of the Wenehuan earthquake. After the Wenchuan earthquake, which happened on 12 May 2008, 30 aftershocks have been recorded in these monitoring points. We analyzed 11 records, with magnitudes ranging from ML = 4.6 to ML = 3.1. The amplification factors of the horizontal compound PGA and 3D compound PGA have been determined for the 3 points at different elevations on the slope. Results showed that the dynamic response of the slope on the earthquake was controlled by factors such as topography and the thickness of the Quaternary overburden.
文摘Between 1850 and 1900, state geological surveys in the Midwest underwent an ideological shift by transforming from institutions based on applied science to those based on pure science. Three factors influenced this process: the acquisition of permanent status from state governments, the establishment of the USGS (United States Geological Survey), and the increase in regional professional scientific societies and publications in the Midwest. These factors aided in the transformation of research projects by state geologists. These projects grew more focused, of higher quality, and increased in number during this time-period. State governments still expected Midwestern geological surveys to meet the practical needs of their respective states as this transformation continued, but surveys complemented these goals with projects more closely related to pure science. This shift encouraged the research goals of surveys to investigate projects more closely related to pure scientific pursuits, and significantly aided in the growth of the earth sciences in the nineteenth Century and early twentieth Century.
基金support from the US National Science Foundation grant(NSF DEB 04-21530)the National Natural Science Foundation of China(30590370).
文摘Global land cover data products are key sources of information in understanding the complex interactions between human activities and global change. They play a critical role in improving performances of ecosystem, hydrological and atmospheric models. Three freely available global land cover products developed in the United States are popularly used by the scientific community. These include two global maps developed separately by the United States Geological Survey (USGS) and the University of Maryland (UMD) with NOAA Advanced Very High Resolution Radiometer ( AVHRR ) data, and one developed by Boston University with the EOS Moderate Resolution Imaging Spectroradiometer ( MODIS) data. They are compared with known land cover types at 250 available Fluxnet sites around the world. The overall accuracies are 37%, 36% and 42%, respectively for the USGS, UMD and Boston global land cover maps, Some future global land cover mapping strategies are suggested.