Uranium concentrations and /sup 234/U//sup 238/U activity ratios in fault-associated groundwater as possible earthquake precursors
In order to assess the utility of uranium isotopes as fluid phase earthquake precursors, uranium concentrations and /sup 234/U//sup 238/U activity ratios have been monitored on a monthly or bimonthly basis in water from 24 wells and springs associated with Southern California fault zones. Uranium concentrations vary from 0.002 ppb at Indian Canyon Springs on the San Jacinto fault to 8.3 ppb at Lake Hughes well on the San Andreas fault in the Palmdale area. /sup 234/U//sup 238/U activity ratios vary from 0.88 at Agua Caliente Springs on the Elsinore fault to 5.4 at Niland Slab well on the San Andreas fault in the Imperial Valley. There was one large earthquake in the study area during 1979, the 15 October 1979 M = 6.6 Imperial Valley earthquake. Correlated with this event, uranium concentrations varied by a factor of more than 60 and activity ratios by a factor of 3 at the Niland Slab site, about 70 km from the epicenter. At the other sites monitored, uranium concentrations varied in time, but with no apparent pattern, while uranium activity ratios remained essentially constant throughout the monitoring period.
- Research Organization:
- Scripps Institution of Oceanography, S-002, La Jolla, CA. 92093
- OSTI ID:
- 6336072
- Journal Information:
- Geophys. Res. Lett.; (United States), Vol. 8:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
EARTHQUAKES
FORECASTING
PRECURSOR
GROUND WATER
ISOTOPE RATIO
NATURAL RADIOACTIVITY
URANIUM
RADIOECOLOGICAL CONCENTRATION
SEISMICITY
URANIUM 234
URANIUM 238
VARIATIONS
WELLS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ACTINIDES
ALPHA DECAY RADIOISOTOPES
ECOLOGICAL CONCENTRATION
ELEMENTS
EVEN-EVEN NUCLEI
HEAVY NUCLEI
HYDROGEN COMPOUNDS
ISOTOPES
METALS
NUCLEI
OXYGEN COMPOUNDS
RADIOACTIVITY
RADIOISOTOPES
SEISMIC EVENTS
URANIUM ISOTOPES
WATER
YEARS LIVING RADIOISOTOPES
580201* - Geophysics- Seismology & Tectonics- (1980-1989)
520300 - Environment
Aquatic- Radioactive Materials Monitoring & Transport- (1989)