instability associated Land cover change can lead to slope by accelerating erosive processes with agriculture, forestry, and infrastructure. The Rio Chiquito-Barranca del Muerto subbasin has experienced an increase in...instability associated Land cover change can lead to slope by accelerating erosive processes with agriculture, forestry, and infrastructure. The Rio Chiquito-Barranca del Muerto subbasin has experienced an increase in land cover change due to government programs and the establishment of agricultural and urban areas. The aim of this study was to provide a model to map the susceptibility to gravitational processes along sites where anthropogenic land cover change has occurred. The method was based on the stratification of the subbasin according to landforms and cartographic variables. These variables were used in a multi- criteria assessment to assign weights according to their contribution to the onset of new gravitationalprocesses. Those weights were used to create a susceptibility map based on a weighted linear sum. The accuracy of the resulting map was validated in an error matrix with a random stratified design based on susceptibility classes per landform. The results produced a map of areas with susceptibility to gravitational processes due to land cover change; this susceptibility is very high in the undifferentiated pyroclastic slope and limestone mountain, where it derives not only from anthropogenie effects on natural vegetation cover, but also from steep slopes, weathered materials, low apparent density, high erosivity, and previous gravitational processes. The results support other studies that concluded that loss of vegetation is a triggering factor in the formation of gravitational processes, but also show that excessive reforestation can increase gravitational processes.展开更多
The remaining fault scarps of a collapsed structure at 32 ka,named Tetelzingo crater,that included Citlaltépetl(CT)volcano,and the associated gravity field,are the basis of a reconstruction of the structures invo...The remaining fault scarps of a collapsed structure at 32 ka,named Tetelzingo crater,that included Citlaltépetl(CT)volcano,and the associated gravity field,are the basis of a reconstruction of the structures involved.The gravity field is obtained from the GGMplus model,from which 3D inversions at resolutions of 1000,500,and 250 m are performed.Low-gravity anomalies are associated with Sierra Negra(4580 m)and Citlaltépetl(5521 m)volcanoes,as well as with the Chichimeco Dome Complex(~4000 m)(CDC).They are located within a SW-NE anomaly that serves as a constraint to the reconstruction.The associ-ated Bouguer anomaly appears as a continuous low-gravity surface;however,its vertical derivative Dz shows that the sources of those three structures are separated.The fault scarps are complemented with inferred trajectories that suggest the existence of two volcanoes before the collapse at 32 ka:Citlaltépetl and the Ancestral Teteltzingo.Density cross-sections identify three stratified magmatic deposits under the summit of CT.On the summit of CT,there is an anomalous concentration of high-density materials,attributed to the presence of domes and lava flows,which mask the position of the volcano’s chimney.The existence of the Ancestral Teteltzingo volcano(ATE)is inferred NE of CT from the associated density distribution;CDC is at the center of the ATE struc-ture and is interpreted as a resurgent activity at<8 ka.Sierra Negra volcano(SN)shows low-density distributions in and around its summit,contradicting the idea that this is an extinct volcano.展开更多
基金PAPIIT IN102115 projectprogram Basic Science SEP-CONACYT(167495)+1 种基金CONACYT scholarship program(328294)Postgraduate Program in Geography,UNAM
文摘instability associated Land cover change can lead to slope by accelerating erosive processes with agriculture, forestry, and infrastructure. The Rio Chiquito-Barranca del Muerto subbasin has experienced an increase in land cover change due to government programs and the establishment of agricultural and urban areas. The aim of this study was to provide a model to map the susceptibility to gravitational processes along sites where anthropogenic land cover change has occurred. The method was based on the stratification of the subbasin according to landforms and cartographic variables. These variables were used in a multi- criteria assessment to assign weights according to their contribution to the onset of new gravitationalprocesses. Those weights were used to create a susceptibility map based on a weighted linear sum. The accuracy of the resulting map was validated in an error matrix with a random stratified design based on susceptibility classes per landform. The results produced a map of areas with susceptibility to gravitational processes due to land cover change; this susceptibility is very high in the undifferentiated pyroclastic slope and limestone mountain, where it derives not only from anthropogenie effects on natural vegetation cover, but also from steep slopes, weathered materials, low apparent density, high erosivity, and previous gravitational processes. The results support other studies that concluded that loss of vegetation is a triggering factor in the formation of gravitational processes, but also show that excessive reforestation can increase gravitational processes.
基金supported by IIMAS and the Geophysics Institute,both at UNAMmaterial support from both institutions.This research did not receive any specific grant from funding agencies in the public,commer-cial,or nonprofit sectors.
文摘The remaining fault scarps of a collapsed structure at 32 ka,named Tetelzingo crater,that included Citlaltépetl(CT)volcano,and the associated gravity field,are the basis of a reconstruction of the structures involved.The gravity field is obtained from the GGMplus model,from which 3D inversions at resolutions of 1000,500,and 250 m are performed.Low-gravity anomalies are associated with Sierra Negra(4580 m)and Citlaltépetl(5521 m)volcanoes,as well as with the Chichimeco Dome Complex(~4000 m)(CDC).They are located within a SW-NE anomaly that serves as a constraint to the reconstruction.The associ-ated Bouguer anomaly appears as a continuous low-gravity surface;however,its vertical derivative Dz shows that the sources of those three structures are separated.The fault scarps are complemented with inferred trajectories that suggest the existence of two volcanoes before the collapse at 32 ka:Citlaltépetl and the Ancestral Teteltzingo.Density cross-sections identify three stratified magmatic deposits under the summit of CT.On the summit of CT,there is an anomalous concentration of high-density materials,attributed to the presence of domes and lava flows,which mask the position of the volcano’s chimney.The existence of the Ancestral Teteltzingo volcano(ATE)is inferred NE of CT from the associated density distribution;CDC is at the center of the ATE struc-ture and is interpreted as a resurgent activity at<8 ka.Sierra Negra volcano(SN)shows low-density distributions in and around its summit,contradicting the idea that this is an extinct volcano.
