Low Resistivity Structure Research Articles

Application of resistivity surveying to geothermal exploration in the Puga valley, India

D.C. resistivity surveys carried out in the Puga valley geothermal field have delineated an elongated, narrow, low resistivity structure, partly underlain by a gas-vapour zone. The resistivity sounding, profiling and traverse data together suggest the channellised flow of hot fluids. The data further show that the eastern and western parts of the valley are devoid of subsurface formations saturated with hot waters.

Audiomagnetotelluric profiling on the volcano stromboli, internal structure and mechanism of the strombolian activity

The audiomagnetotelluric profiling method has found exceptional utility in detecting anomalies of shallow resistivities associated with intrusive dikes and active lava channels on Stromboli volcano. Using a computerized finite element method, it has been shown that the important lateral contrast of the measured apparent resistivity along different profiles represents realistic situations of vertical conductive structures buried in the volcanic grounds. Self-potential measurements and field observations have suggested that the conductive bodies are present at shallow depth. A good knowledge of the lateral extent of these hot active zones has provided insights into the upper internal structure of the volcano. The elongated zones between two large low-resistivity structures in the south and the craters in the northwest deepen from the southeast to the northwest. This geometrical layout strongly suggests an explanation of the strombolian eruptions in which the flow of lava temporarily blocks part of the path of the gases. The plug of lava cools and the increase in pressure of the gases, once it becomes greater than the resistance of viscosity, ejects the mass of lava which shatters on leaving the vent and gives rise to the well-known effect of well-collimated jets of gases loaded with hot spatter and scoria which is characteristic of strombolian activity.