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Title: Onshore and offshore measurements of temperature gradients in the Salton Sea geothermal area, California

Abstract

By removing the effect of the annual temperature cycle with an iterative least-squares method, geothermal gradients at 44 sites were determined from onshore and offshore temperature measurements at depths less than 16 and 2 m, respectively, around the southeastern end of the Salton Sea (water depth < 20 m). Onshore temperatures were measured at 1-m intervals in drill holes cased with 0.25-inch PVC pipes and offshore temperatures were obtained with a 2-m lance-like thermal probe (0.50-inch OD) which contains 7 equally spaced thermistor sensors. The gradients range from 0.02/sup 0/ to 1.7/sup 0/C/m and from 0.72/sup 0/ to 4.3/sup 0/C/m in the onshore and offshore areas, respectively. Heat fluxes, calculated from an assumed value of heat capacity, and in-situ determined thermal diffusivities and gradients, decrease away from a chain of four Quaternary volcanic domes, near the present shoreline. Superimposed on this general trend are several sites with high heat flux, reflecting local hydrological influence. Corrections for sedimentation, for presence of the lake, or for disturbance around the thermal probe may individually exceed 0.030/sup 0/C/m (normal geothermal gradient of the upper curst); however, the net effects cannot account for the disparity between the onshore and offshore data sets. Even if themore » offshore gradients are divided by a factor of 3 to make the two sets of data compatible, these new data (together with data from 22 onshore sites measured previously) indicate the offshore anomaly covers an area at least the size of the onshore anomaly, defined somewhat arbitrarily as an area with heat flux greater than 200 x 10/sup -3/ W/m/sup 2/.« less

Authors:
;
Publication Date:
Research Org.:
Univ. of California, Riverside
OSTI Identifier:
6305733
Resource Type:
Journal Article
Journal Name:
Geophysics; (United States)
Additional Journal Information:
Journal Volume: 44:2
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; SALTON SEA GEOTHERMAL FIELD; GEOTHERMAL GRADIENTS; BOREHOLES; CALIFORNIA; HEAT FLOW; HYDROLOGY; SALTON SEA; SEDIMENTATION; SPECIFIC HEAT; TEMPERATURE MEASUREMENT; THERMAL DIFFUSIVITY; CAVITIES; GEOTHERMAL FIELDS; IMPERIAL VALLEY; NORTH AMERICA; PHYSICAL PROPERTIES; TEMPERATURE GRADIENTS; THERMODYNAMIC PROPERTIES; USA; WESTERN REGION; 150301* - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys

Citation Formats

Lee, T.C., and Cohen, L.H. Onshore and offshore measurements of temperature gradients in the Salton Sea geothermal area, California. United States: N. p., 1979. Web. doi:10.1190/1.1440962.
Lee, T.C., & Cohen, L.H. Onshore and offshore measurements of temperature gradients in the Salton Sea geothermal area, California. United States. doi:10.1190/1.1440962.
Lee, T.C., and Cohen, L.H. Thu . "Onshore and offshore measurements of temperature gradients in the Salton Sea geothermal area, California". United States. doi:10.1190/1.1440962.
@article{osti_6305733,
title = {Onshore and offshore measurements of temperature gradients in the Salton Sea geothermal area, California},
author = {Lee, T.C. and Cohen, L.H.},
abstractNote = {By removing the effect of the annual temperature cycle with an iterative least-squares method, geothermal gradients at 44 sites were determined from onshore and offshore temperature measurements at depths less than 16 and 2 m, respectively, around the southeastern end of the Salton Sea (water depth < 20 m). Onshore temperatures were measured at 1-m intervals in drill holes cased with 0.25-inch PVC pipes and offshore temperatures were obtained with a 2-m lance-like thermal probe (0.50-inch OD) which contains 7 equally spaced thermistor sensors. The gradients range from 0.02/sup 0/ to 1.7/sup 0/C/m and from 0.72/sup 0/ to 4.3/sup 0/C/m in the onshore and offshore areas, respectively. Heat fluxes, calculated from an assumed value of heat capacity, and in-situ determined thermal diffusivities and gradients, decrease away from a chain of four Quaternary volcanic domes, near the present shoreline. Superimposed on this general trend are several sites with high heat flux, reflecting local hydrological influence. Corrections for sedimentation, for presence of the lake, or for disturbance around the thermal probe may individually exceed 0.030/sup 0/C/m (normal geothermal gradient of the upper curst); however, the net effects cannot account for the disparity between the onshore and offshore data sets. Even if the offshore gradients are divided by a factor of 3 to make the two sets of data compatible, these new data (together with data from 22 onshore sites measured previously) indicate the offshore anomaly covers an area at least the size of the onshore anomaly, defined somewhat arbitrarily as an area with heat flux greater than 200 x 10/sup -3/ W/m/sup 2/.},
doi = {10.1190/1.1440962},
journal = {Geophysics; (United States)},
number = ,
volume = 44:2,
place = {United States},
year = {1979},
month = {2}
}