Modeling-Computer Simulations At Long Valley Caldera Geothermal Area (Farrar, Et Al., 2003)
Exploration Activity: Modeling-Computer Simulations At Long Valley Caldera Geothermal Area (Farrar, Et Al., 2003)
|Exploration Activity Details|
|Location||Long Valley Caldera Geothermal Area|
|Exploration Technique||Modeling-Computer Simulations|
|Activity Date||2001 - 2003|
The study integrates detailed results from pump tests, fluid level monitoring, temperature logging, and fluid sampling/analysis of the LVEW with information obtained from other wells drilled on or near the resurgent dome to provide a comprehensive conceptual model of the different stages of hydrothermal activity, flow, and recharge in the Long Valley caldera groundwater system.
The pressure data obtained during the September 2001 flow test at LVEW are best matched using modeled solutions for a flow system consisting of a rock matrix with finite hydraulic conductivity cut by a steeply dipping fracture with infinite hydraulic conductivity. For this model to match the pressure data the horizontal extent of the fracture zone was assumed to be a few hundred meters and a constant head boundary was assigned at a distance of 100 to 400 m from the wellbore. The best fit model for the measured pressure data uses a transmissivity value of 10-5 m2/s and storage coefficients between 10-6 and 10-5 for the matrix surrounding main the fracture zone. The results of the flow testing together with analysis of water level changes across the resurgent dome suggest the fracture zone in LVEW can transmit pressure changes over hundreds to thousands of meters over short time periods (days). Continuous pressure monitoring of the LVEW could therefore be useful in detecting pressure changes associated with inputs of new magma or hydrothermal fluid into the shallow crust beneath the resurgent dome.
- Christopher D. Farrar, Michael L. Sorey, Evelyn Roeloffs, Devin L. Galloway, James F. Howle, Ronald Jacobson (2003) Inferences On The Hydrothermal System Beneath The Resurgent Dome In Long Valley Caldera, East-Central California, USA, From Recent Pumping Tests And Geochemical Sampling