Additional audio-magnetotelluric soundings in the Lassen Known Geothermal Resource Area, Plumas and Tehama counties, California

Measurements of thermal-water discharge outside Lassen Volcanic National Park, California, 1983-94

“…The pattern of low resistivity anomalies corresponds reasonably well with outflow zones that surface along Mill Creek and at Domingo Springs (Sorey and Ingebritsen, 1984;Christopherson and Pringle, 1981). Most of the dozen or so test holes drilled in the Lassen KGRA show low temperature gradients indicative of ground-water recharge or conductive gradients associated with regional heat flow values near 70 mW/m2 (Mase and others, 1980).…”

“…The orientation of this outflow zone appears to be fault controlled, following traces of the Hot Springs Creek and Terminal Geyser faults as mapped by Clynne (1984Clynne ( , 1990. Regions of low electrical resistivity extend along this outflow zone as it passes beneath the Park boundary and are also delineated in the vicinity of Domingo Springs (Sorey and Ingebritsen, 1984;Christopherson and Pringle, 1981). Direct evidence of a hot-water aquifer along this outflow zone comes from temperature profiles and fluid chemistry data for the Walker "0" No.…”

Mineral and geothermal resource potential of Wild Cattle Mountain and Heart Lake Roadless Areas, Plumas, Shasta, and Tehama counties, California

“…Substantial geophysical investigations have been carried out by the USGS in connection with pre-lease evaluation of Lassen KGRA (Christopherson, 1980;Christopherson and Pringle, 1981;Christopherson and others, 1980;Mase and others, 1980;Christopherson and Hoover, 1981;Dighem, Ltd., 1982). In addition, the USGS maintains an eight-station seismic network in and around the Park (Klein, 1979;D.…”

“…The presence of siliceous sinter at Morgan and Growler Hot Springs indicates that the thermal waters at depth are almost certainly over 180°C (White, 1974), and Na-K-Ca, sulfate-isotope, and mixing-model geothermometers indicate that the deep thermal water feeding these springs may have a temperature approaching 240°C (Brook and others, 1979; J. M. Thompson, oral communication, 1982). Audio-magnetotel1 uric, telluric, self-potential, magnetotelluric, and airborne electromagnetic surveys have been conducted in Lassen KGRA (Christopherson, 1980;Christopherson and others, 1980;Christopherson and Pringle, 1981;Christopherson and Hoover, 1981;Dighem Ltd., 1982). These surveys all display a complex pattern of resistivity reflecting primarily near-surface variations in lithology, porosity, and temperature.…”

Measurements of heat and mass flow from thermal areas in Lassen Volcanic National Park, California, 1984-93

“…4), include Bumpass Hell, Little Hot Springs Valley, Sulphur Works, Pilot Pinnacle, and Lassen Peak itself. Areas in set 2, which occur along easterly and southeasterly trending fault zones and are underlain by a region of low electrical resistivity (Christopherson and Pringle, 1981;Sorey and Ingebritsen, 1984), include Devils Kitchen, Drakesbad, Boiling Springs Lake, and Terminal Geyser.…”