Large earthquakes cause observable changes in the Earth’s gravity field, which have been detected by the Gravity Recovery and Climate Experiment (GRACE). Since most previous studies focus on the detection of near-fie...Large earthquakes cause observable changes in the Earth’s gravity field, which have been detected by the Gravity Recovery and Climate Experiment (GRACE). Since most previous studies focus on the detection of near-field gravity effects, this study provides the results from the medium- to far-field gravity changes caused by the 2004 Sumatra-Andaman earthquake that are recorded within GRACE monthly solutions. Utilizing a spherical-earth dislocation model we documented that large-scale signals predominate in the global field of the coseismic gravity changes caused by the earthquake. After removing the near-field effects, the coseismic gravity changes show a negative anomaly feature with an average magnitude of -0.18×10-8 m·s-2 in the region ranging ～40° from the epicenter, which is considered as the 'medium ffield' in this study. From the GRACE data released by Center for Space Research from August 2002 to December 2008, we retrieved the large-scale gravity changes smoothed with 3 000 km Gaussian ffilter. The results show that the coseismic gravity changes detected by GRACE in the medium field have an average of (-0.20±0.06)×10-8 m·s-2, which agrees with the model prediction. The detection confirms that GRACE is sensitive to large-scale medium-field coseismic gravitational effects of mega earthquakes, and also validates the spherical-earth dislocation model in the medium field from the perspective of satellite gravimetry.展开更多
Understanding housing preferences is critical for successful compact city development.However,there is limited research on understanding preference heterogeneity in dwelling type choices.Using the Household Income and...Understanding housing preferences is critical for successful compact city development.However,there is limited research on understanding preference heterogeneity in dwelling type choices.Using the Household Income and Labour Dynamics in Australia survey,this paper identifies the key housing and built environment characteristics associated with changes in dwelling type choice from detached houses to high-density.A latent class choice model captures the heterogeneity of dwelling type preferences within a traditionally low-density city,Brisbane,Australia.Findings reveal six household classes with distinct dwelling preferences:Class 1(senior households without children with other family members)and Class 2(couple families with children)in inner-city areas,Class 3(high-income young households)and Class 4(low-income households without children)in middle-city areas,Class 5(low-income families with children)and Class 6(middle-income young families without children)in outer-city areas.Residential environments with better access to educational facilities encourage Classes 3 and 6 to change to high-density living.Greater land use diversity encourages Classes 2,3,and 6 to move towards high-density living.Thefindings can be used to design and improve high-density housing for targeted population groups across inner-,middle-and outer-city areas.展开更多
基金funded in parts by the Natural Science Foundation of China (grant Nos. 40974015, 41128003, 41174011 and41021061)the Open Fund of Key Laboratory of Geo-dynamic Geodesy of Chinese Academy (No. 09-18)the Open Fund of Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, China (No.07-12)
文摘Large earthquakes cause observable changes in the Earth’s gravity field, which have been detected by the Gravity Recovery and Climate Experiment (GRACE). Since most previous studies focus on the detection of near-field gravity effects, this study provides the results from the medium- to far-field gravity changes caused by the 2004 Sumatra-Andaman earthquake that are recorded within GRACE monthly solutions. Utilizing a spherical-earth dislocation model we documented that large-scale signals predominate in the global field of the coseismic gravity changes caused by the earthquake. After removing the near-field effects, the coseismic gravity changes show a negative anomaly feature with an average magnitude of -0.18×10-8 m·s-2 in the region ranging ～40° from the epicenter, which is considered as the 'medium ffield' in this study. From the GRACE data released by Center for Space Research from August 2002 to December 2008, we retrieved the large-scale gravity changes smoothed with 3 000 km Gaussian ffilter. The results show that the coseismic gravity changes detected by GRACE in the medium field have an average of (-0.20±0.06)×10-8 m·s-2, which agrees with the model prediction. The detection confirms that GRACE is sensitive to large-scale medium-field coseismic gravitational effects of mega earthquakes, and also validates the spherical-earth dislocation model in the medium field from the perspective of satellite gravimetry.
文摘Understanding housing preferences is critical for successful compact city development.However,there is limited research on understanding preference heterogeneity in dwelling type choices.Using the Household Income and Labour Dynamics in Australia survey,this paper identifies the key housing and built environment characteristics associated with changes in dwelling type choice from detached houses to high-density.A latent class choice model captures the heterogeneity of dwelling type preferences within a traditionally low-density city,Brisbane,Australia.Findings reveal six household classes with distinct dwelling preferences:Class 1(senior households without children with other family members)and Class 2(couple families with children)in inner-city areas,Class 3(high-income young households)and Class 4(low-income households without children)in middle-city areas,Class 5(low-income families with children)and Class 6(middle-income young families without children)in outer-city areas.Residential environments with better access to educational facilities encourage Classes 3 and 6 to change to high-density living.Greater land use diversity encourages Classes 2,3,and 6 to move towards high-density living.Thefindings can be used to design and improve high-density housing for targeted population groups across inner-,middle-and outer-city areas.
