Several faults have been mapped in the vicinity of Vallejo. The San Andreas Fault and Hayward Faults are the most active faults, although the San Andreas is at some distance. Locally, the Sulphur Springs Valley Thrust Fault and Southampton Fault are found. No quaternary seismic activity along these minor faults has been observed with the possible exception of a slight offset revealed by trenching. The Sulphur Mountain and Green Valley faults have been associated with the Concord Fault to the south. The Concord Fault is considered active. Historically there have been local cinnabar mines in the Vallejo area. The Hastings Mine and St. John's Mine contribute ongoing water contamination for mercury; furthermore, mine shaft development has depleted much of this area's spring water. Both Rindler Creek and Blue Rock Springs Creek have been affected.