Changing mercury anomalies in Long Valley, California: indication for magma movement or seismic activity ( USA).

Comparison of the Hg distribution in Long Valley, measured in 1975 and again in 1982, indicate that a new Hg anomaly formed in the Inyo crater zone in the intervening period. Two models can explain this new anomaly: 1) geothermal water has reached shallow levels as a result of increased permeability created by seismic activity, and 2) addition of a CO₂-rich, magnetic vapour to the geothermal system at depth caused vapor exsolution in zones where it did not occur before. If the Hg anomaly in the Inyo crater zone is related to the addition of magmatic vapors, the site of the new anomaly may overlie young, intruding magma.-from Authors