Characterization of Geological Targets in Karst Terrains with Seismic Arrays
Lanbo LIU#+
Department of Civil & Environmental Engineering, United States

Globally, the widely extended karst terrains poses great challenges to urban development, groundwater resources, waste water contamination control, and subsurface geotechnical engineering. Narrow down to geotechnical engineering, sinkholes, dissolved channels and networks, caves and voids certainly complicate the design, construction, and maintenance of any projects sited in karst geology. As an indirect and cost-effective approach, the seismic method using both active and passive sources and deployed either on land surface, or in underground in tunnels or boreholes, or even simultaneously on both surface and subsurface, is one of the most powerful tools to provide credible information of karst environments, in conjunction with the direct excavation by drilling, trenching, and tunneling.In this talk I will survey and review the effectiveness of a variety of seismic array configurations and seismic source and wave types for tackling the challenge of detection of differrent geological targets in karst terrains. I will illustrate the arguments with numerical simulated cases. Apparently, surface arrays are most effective for laterally extended features like underground rivers; while vertical seismic profiling (VSP) may by more useful for imaging the vertical conduits. A combination of using surface array and array in tunnels may provide more tightly constrained information for imaging the targets in front of tunnel face. In really the challenge is time synchronization of the subsurface and surface arrays.