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Quantitative analysis of the hydrothermal system in Lassen Volcanic National Park and Lassen Known Geothermal Resource Area

Water-Resources Investigations Report 84-4278

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Abstract

The conceptual model of the Lassen system is termed a liquid-dominated hydrothermal system with a parasitic vapor-dominated zone. The essential feature of this model is that steam and steam-heated discharge at relatively high elevations in Lassen Volcanic National Park (LVNP) and liquid discharge with high chloride concentrations at relatively low elevations outside LVNP are both fed by an upflow of high-enthalpy two-phase fluid within the Park. Liquid flows laterally away from the upflow area towards the areas of high-chloride discharge, and steam rises through a vapor-dominated zone to feed the steam and steam-heated features. Numerical simulations show that several conditions are necessary for the development of this type of system, including (1) large-scale topographic relief, (2) an initial period of convective heating within an upflow zone followed by some change in hydrologic or geologic conditions that initiates drainage of liquid from portions of the upflow zone, and (3) low permeability barriers that inhibit the movement of cold water into the vapor zone. Simulations of thermal fluid withdrawal south of LVNP, carried out in order to determine the effects of such withdrawal on portions of the hydrothermal system within the Park, showed decreases in pressure and liquid saturation beneath the vapor zone which result in a temporary increase and subsequent decrease in the rate of upflow of steam. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Quantitative analysis of the hydrothermal system in Lassen Volcanic National Park and Lassen Known Geothermal Resource Area
Series title:
Water-Resources Investigations Report
Series number:
84-4278
Edition:
-
Year Published:
1984
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
viii, 80 p. :ill., maps ;28 cm.