This study tries to highlight the role of magnetic and seismic data in the prevention of building cracking, which constitutes a geotechnical risk in Agadez City. This city is built on the faulted and fractured sandsto...This study tries to highlight the role of magnetic and seismic data in the prevention of building cracking, which constitutes a geotechnical risk in Agadez City. This city is built on the faulted and fractured sandstone formations of the “Agadez Sandstones Formations”, which were deposited in unconformity on the basement of the Aïr Mountain. This study focuses on the prevention of geotechnical damages related to building cracking in the Agadez region through geophysical methods, which are well known for investigating tectonic structures and their directions on the surface and subsurface. A methodological approach integrated the seismic and magnetic data interpretation combined with field measurement on the cracked building and its underlying substratum, represented by Agadez sandstones and basement. The extraction of seismic lineaments from the West African seismic map showed the seismic directions oriented NW-SE (N135˚ to N160˚), passing through the studied area. The structural interpretation of the magnetic map shows that the Agadez region is also affected by the subsurface lineaments mainly oriented in NW-SE (N135˚) directions, which are similar to the identified seismic lineaments in the same zone. A structural study carried out on the Agadez sandstones and the underlying basement showed that faults and fractures oriented N120˚ to N165˚ affect both the basement of the Aïr Mountains and the sandstone formations on which the city of Agadez is built. These observations showed that building cracking in the Agadez region has a higher propagation tendency according to the directions ranging from NW-SE (N135˚) to NNW-SSE (N165˚). Therefore, the building’s cracking has a stronger propagation component according to these mean directions that are not recommended for building. To prevent and reduce the risks related to building cracking in Agadez region, it is highly recommended to build in the minor directions of cracking propagation, which correspond to NE and SW directions.展开更多
文摘This study tries to highlight the role of magnetic and seismic data in the prevention of building cracking, which constitutes a geotechnical risk in Agadez City. This city is built on the faulted and fractured sandstone formations of the “Agadez Sandstones Formations”, which were deposited in unconformity on the basement of the Aïr Mountain. This study focuses on the prevention of geotechnical damages related to building cracking in the Agadez region through geophysical methods, which are well known for investigating tectonic structures and their directions on the surface and subsurface. A methodological approach integrated the seismic and magnetic data interpretation combined with field measurement on the cracked building and its underlying substratum, represented by Agadez sandstones and basement. The extraction of seismic lineaments from the West African seismic map showed the seismic directions oriented NW-SE (N135˚ to N160˚), passing through the studied area. The structural interpretation of the magnetic map shows that the Agadez region is also affected by the subsurface lineaments mainly oriented in NW-SE (N135˚) directions, which are similar to the identified seismic lineaments in the same zone. A structural study carried out on the Agadez sandstones and the underlying basement showed that faults and fractures oriented N120˚ to N165˚ affect both the basement of the Aïr Mountains and the sandstone formations on which the city of Agadez is built. These observations showed that building cracking in the Agadez region has a higher propagation tendency according to the directions ranging from NW-SE (N135˚) to NNW-SSE (N165˚). Therefore, the building’s cracking has a stronger propagation component according to these mean directions that are not recommended for building. To prevent and reduce the risks related to building cracking in Agadez region, it is highly recommended to build in the minor directions of cracking propagation, which correspond to NE and SW directions.
